Lathe Threading Inserts  - Page 1
Forum section: electronics / general

author: tautech
author_rank: Super Contributor
timestamp: December 10, 2022, 08:46:57 am
content: Please some advice on the finer points of threading with carbide inserts.External only at this time so to be able to learn to crawl before advancing to anything more complex.Looking to get some triangle inserts for my ordinary triangle turning insert holders and seeking advice on setting rakes and for which metals might need + or - rakes for threading.Threading with HSS tooling is no problem and prefer a compound slide plunge as opposed to the single point cross slide technique but looking to venture into carbide and single point threading.Trouble is, what's all this about shims ?First mentioned here on P11http://www.mitsubishicarbide.com/application/files/3815/7587/4149/c009n_g_threading.pdfNeed worry about this stuff in the home workshop or not ?

author: Ian.M
author_rank: Super Contributor
timestamp: December 10, 2022, 09:19:48 am
content: Perhaps this will help:https://www.machiningdoctor.com/glossary/lead-angle/Whether or not you need to bother shimming under the insert depends on if your thread's lead angle is small enough for acceptable flank clearance on the leading side with the insert flat, and if not, for external threading only, whether your toolholder permits slightly tilting the tool about its axis to put the top of the tool tip normal to the thread helix.

author: Benta
author_rank: Super Contributor
timestamp: December 10, 2022, 07:54:30 pm
content: For thread turning, you'd normally use inserts like these:https://www.hoffmann-group.com/GB/en/houk/Machining/Turning/Thread-turning-tools/c/10-03-03-00-00?tId=867Simple 60 degrees triangular inserts normally don't have the geometry for thread turning.

author: tautech
author_rank: Super Contributor
timestamp: December 10, 2022, 08:38:16 pm
content: Quote from: Benta on December 10, 2022, 07:54:30 pmThanks, yes of course using proper threading inserts like those was always the plan and from your link I learnt more today, that being inserts are available in Full or Partial profile styles.That poses a further question, for versatility would a 55 degree partial profile be better so to permit 30ocompound slide use for 60othreads so to not need to keep 60oinserts too ?Actually thinking about that more, using a 55oinsert will require a 32.5osetting on the compound slide to produce a full 60othread form. Hmmm.Yeah I'm a tightwad.Thanks guys.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 10, 2022, 09:03:26 pm
content: 55° included angle is a Whitworth thread. My British lathe (circa 1966) has that thread everywhere as did the objectives on microscopes I have used. It is considerably deeper. Nominal sizes don't fit together "right" with 60° threads. You could probably screw around with the PD to make them feel better, but why not go with 60°?BTW, a strange "American" thread -- namely 1/2"x12 -- seems to be used in Taiwan. I have had two items from Taiwan that used that thread. One actually has the 55° profile. It's an inexpensive horizontal bandsaw from Harbor Freight. I kept it, as its application in that device seemed reasonable. The other item was adjusting feet on the vertical poles for a steel wire rack. I did not check the angle. I returned it, as getting decent casters for it would be a nightmare and probably impossible. The casters made in Taiwan and available from the American dealer were not double locking.For lathe threading, I use a threading insert holder by Kennametal and appropriate inserts that are not always the partial profile version.Sorry for the somewhat random musings.BTW#2: My oldest grandchild is spending next semester in NZ from the University of Vermont.

author: Benta
author_rank: Super Contributor
timestamp: December 10, 2022, 09:32:01 pm
content: Don't go there.Stick with standard 60 degrees inserts. Unless you're working with old British cars, odds are you'll never need a 55 degrees type. Should it happen, then grind a HSS cutter for the purpose.

author: tautech
author_rank: Super Contributor
timestamp: December 10, 2022, 09:47:06 pm
content: Quote from: jpanhalt on December 10, 2022, 09:03:26 pmIIRC BSPT is 55 too so it would be nice to be able to do those too but not all BSPT I can as some need specialist changewheels to produce the correct threading pitch.I do have BSPT dies but not under 1/2" where I do occasionally require 3/8 and 1/4 gas as we call them.QuoteYep for some modern stuff a thread gauge and thread chart are indispensable !QuoteHoping I can get away with just normal triangular insert holders of which I have a few but 16 and 22mm get the most use. Thinking partial will do what I need but I need some more clarity on shimming and if I need also invest in them or just say stuff it and keep grinding HSS for threading.QuoteQuoteWhere ? Studying ? Subject ?

author: tautech
author_rank: Super Contributor
timestamp: December 10, 2022, 09:49:01 pm
content: Quote from: Benta on December 10, 2022, 09:32:01 pmYep, starting to get that feeling too.BSF and BSW are pretty rare now my Landy is gone.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 10, 2022, 09:51:26 pm
content: Small addition: Just realized you were asking about using a 55° insert for turning 60°threads. I have two lathes. The smaller is apartment size -- an SD300 Prazi -- it's a toy. For that, I used a 60° insert and advanced the tool holder at an angle to avoid chatter. It is really not very rigid. With a rigid lathe, that may not be necessary.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 10, 2022, 09:58:01 pm
content: Quote from: tautech on December 10, 2022, 09:47:06 pmI don't know yet. He is into environmental science and loves the outdoors. They (he and family) are visiting at Christmas. His mom told me today that he finally got his visa. I had a post-doc student from NZ in the mid-90's. She shared some pictures with me. I was struck with the variety you have on an island and its similarity to our Alaska in its grandeur. I envy my grandson.

author: tautech
author_rank: Super Contributor
timestamp: December 10, 2022, 10:27:56 pm
content: Quote from: jpanhalt on December 10, 2022, 09:51:26 pmCompound slide feed while fiddly is what I've done for all my lathe threading and feel very comfortable with it whereas single point threading using only the cross slide in new to me but it seems the most common method if using carbide.Mine's a 3 phase 2sp 3hp Harrison 12, built 1970 with a rare Metric/Imperial change over lever so no fiddling with changewheels required for any of the common threads.This beast but they don't even have any images of one with this M/Imp change over lever:http://www.lathes.co.uk/harrison/page16.htmlWhen I got it a few years back I contacted and sent Lathes UK pictures and invited them to use them online and got a reply saying they'd never seen such a well spec'd one in this model.Some pics attached from when I just got and cleaned it.Change over lever is just above the apron on the gear chest wall.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 10, 2022, 10:40:20 pm
content: Wow, I had a choice between a Harrison toolroom lathe in about 10" (500AA?) and the Smart and Brown. I picked wrongly the Smart and Brown. It's still a great lathe for what I do.

author: Benta
author_rank: Super Contributor
timestamp: December 10, 2022, 10:45:17 pm
content: Nice looking latheJust to get the terminology right: what you've been doing with the compound at 30 or 29.5 degrees, whatever, is "single point cutting". It's called that because only one cutting edge of the insert is in action. This prevents chatter.Going in with the cross-slide only is "direct form/thread cutting" where both cutting adges are active, and needs a really rigid and tight machine, and even then it's difficult. I avoid it if I can, though it's OK for smaller threads.

author: tautech
author_rank: Super Contributor
timestamp: December 10, 2022, 10:47:09 pm
content: Quote from: jpanhalt on December 10, 2022, 10:40:20 pmIIRC the 500's are a quite late model and as such might have some modern features also.There's a Groups Io site where a few of us Harrison owners hang out:https://harrisonlathe.groups.io/g/mainMight be some interesting reading for you there but like for any Groups mob you have to request membership before you can contribute.

author: tautech
author_rank: Super Contributor
timestamp: December 10, 2022, 10:55:07 pm
content: Quote from: Benta on December 10, 2022, 10:45:17 pmThanks.Yep that's what I've been doing with HSS but would like to graduate to carbide.Single point threading doesn't use the compound slide at all and leaves it on 0oand only advances the cross slide for thread depth.Watch some of this:

author: Benta
author_rank: Super Contributor
timestamp: December 11, 2022, 12:21:39 am
content: I don't even need to watch the video. The miserable surface quality is apparent in the photo. The lathe must have been howling when cutting that.

author: tautech
author_rank: Super Contributor
timestamp: December 11, 2022, 12:50:14 am
content: Quote from: Benta on December 11, 2022, 12:21:39 amReally ?There is always something to learn and many mistakes resulting in turning chatter result from not using the tailstock center. Some examples in the video have work full supported and some don't for whatever reason but there are good examples of single point threading where only the cross slide is used, very identifiable from the dual swarf flows from the carbide insert.

author: tautech
author_rank: Super Contributor
timestamp: December 11, 2022, 01:59:35 am
content: Thinking I'll shell out for a turning holder too as this fella seems to have a 2nd screw for geometry adjustment:https://www.ebay.com/itm/284645720497To best match the lathe tool post I need 25mm shank tool holders which does unfortunately push into another price bracket.This seller offers the holder and threading inserts separately for free shipping but costs work out near the same.Brought from him before and he will put a package deal together and give you a private listing.When flush with coin also thinking about upgrading from a tool post like thishttps://de.aliexpress.com/item/1005003745694437.htmlTo something quick change like this:https://www.machineryhouse.co.nz/l294However as it's required to accept 1"/25mm shanks, oh the price !

author: hubi
author_rank: Regular Contributor
timestamp: December 11, 2022, 02:19:03 am
content: I don't do much threading, but I like to use a left hand insert holder upside down and feed left to right. Much less stressful if there is no chance of running the tool into a shoulder. With the carbide inserts, I do not bother to set the compound at 30 degrees but leave it at zero. Works well for me using 4140 steel. Anything under 3/8", I use a threading die.

author: tautech
author_rank: Super Contributor
timestamp: December 11, 2022, 03:08:18 am
content: Quote from: hubi on December 11, 2022, 02:19:03 amI guess every lathe is different as is operator technique.I thread at low speedandalways finish into a relief lower than the root of the thread, furthermore my Harrison has a manual hand clutch/brake arrangement and at low threading speeds it stops travel and work rotation in an instant !Never have I been concerned with this lathe about turning all the way to a shoulder, even in general tuning at high speed stopping under 0.5mm/20 thou from a shoulder is very achievable even when peeling off 1.5mm/60 thou cuts.

author: Ian.M
author_rank: Super Contributor
timestamp: December 11, 2022, 03:45:10 am
content: @tautech,Your proposed toolpost upgrade may actually make it more difficult to get a good surface finish. The higher cutting forces typical of Tungsten carbide insert tooling (due to the higher feeds, speeds, and typically higher depth of cut) demand a lot of rigidity. A four way (turret) toolpost is typically significantly more rigid than a quick change toolpost of comparable dimensions. The disadvantage to the amateur of sticking with a four way toolpost is of course the need for shimming, but if your tooling has sufficiently consistent tip height, you wont need to change the shims much. A production shop also has to consider the setup speed advantages of a quick-change toolpost with enough toolholders, and may compromise on finish to save time.

author: tautech
author_rank: Super Contributor
timestamp: December 11, 2022, 05:05:10 am
content: Quote from: Ian.M on December 11, 2022, 03:45:10 am100%What you say makes a lot of sense, thanks.Yes in some ways it makes more sense to invest it tooling with the same tip height for shimming to be very simple and hopefully identical for all tool holders. With the selection of 'all over the place' tooling I use now and with a small selection of shims, shimming does rob some time. A bigger/better set of shims would allow for taping each set to a tool shank.Earlier today while browsing I stumbled across a nice little tool shank shim set that I can no longer find !It certainly would be a cheaper solution to have all tool shanks the same size and a very closely matched set of tool post shims instead.I normally just set center height to a tailstock center but I'm instead thinking about turning up a center height tool which would speed changing tooling and setting to height much faster and more precise that carbide certainly requires.The neverending fun of making tools to make using your tools more enjoyable !

author: mzzj
author_rank: Super Contributor
timestamp: December 11, 2022, 06:59:14 am
content: Quote from: tautech on December 11, 2022, 01:59:35 amThat is not geometry adjustment screw in the pics, just another clamping screw to keep the insert and/or shim firmly in the pocket.In case it wasn't already clear: Typically you don't need to fool around with the angled shims with any of the standard threads. You need one only if you make something with really high helix angle like super-coarse thread outside of standards or multi-start thread.You can use compound or cross slide, sort of depends on machine and personal preferences.Earlier I was using combination of compound and cross slide as it makes math/counting really easy(increase depth of cut only from compound slide and never retract it. And use crosslide to retract the tool at the end of the cut but set it at same position before each cut)Later on I installed 2-axis DRO and moved to using only cross slide as compound slide didn't have DRO scale and it was easier to work with the DRO numbers alone.And unless you have huge collection of tooling with 25mm shank you can also use smaller QC toolpost. Just set the toolpost higher with piece of steel disk or plate. (have to be flat and smooth but since you have lathe you can always turn it flat)25mm shank tooling is not giving much advantage in home shop use unless you work on really large parts and heavy cuts like turning 1:1 scale steam locomotive axles.Good toolpost in >16mm shank sizes is plenty of rigid for threading with carbide. Typically the ridigity problems are somewhere else.

author: tautech
author_rank: Super Contributor
timestamp: December 11, 2022, 08:10:28 am
content: Quote from: mzzj on December 11, 2022, 06:59:14 amThanks for this confirmation as I did wonder if it was for additional clamping, something plain turning inserts don't need in my experience...which is somewhat limited.QuoteYes, deeper study of the Hoffman PDF from Benta reveals the charts indicating which pitches you can turn without tapered shims....most normal stuff as you say.QuoteAll my threading thus far has been increasing cut depth with the compound slide and backing out and in with the cross slide.Many years back I watched a professional machinist thread stepped bolts to a shoulder and into a relief to stop the lathe with the leadscrew nut engaged, bact the tool out with the cross slide then reverse the lathe and tool along the thread to stop it again, return the cross slide to zero and advance the compound for another pass.This ^ stuck in my mind for decades until I had I had a lathe capable of threading and finally owning a fish tail threading tool.When pressure came on to put all this together for rifle barrel threading to fit a suppressor, practice on a scrap of round stock had me get it right right from the get go and no one was amazed as I was that a small and seemingly useless bit of technique had stuck fast in my grey matter all them years !QuoteCurrent 4 sided tool post in use is a 4" beast which IIRC can take 27mm tooling so 25mm tooling works well with it although I still need shim tools a little.It replaced the smaller 3" tool post that came with this Harrison lathe which couldn't accept 1" tooling and the 4" beast I like better for a few reasons.The most shimming I need do is for a small 14mm square shank bar I made to do small boring between 1/2 and 3/4" where my bigger bars take over.This lathe does show some signs of wear and gib tightness is a compromise but sometimes needs addressing especially for parting where any chatter is a recipe for disaster.Thanks chaps, really enjoying the feedback.

author: Benta
author_rank: Super Contributor
timestamp: December 11, 2022, 05:11:34 pm
content: I have a collection of small zip-lok plastic bags, each containing one tool and matching shims. That makes shimming fast and easy.

author: mag_therm
author_rank: Frequent Contributor
timestamp: December 11, 2022, 05:35:21 pm
content: I have done some threads on my South Bend 9A.A straight 60 degree HS threading tool is for UNF and metric,or the other end at 55 degree for some camera threads ( metric Whitworth).I tried the compound feed method, bu reverted to cross feed ( feeding the tool in at 90 degrees on each pass)There are 2 reasons:1) when using the compound feed, the back force is angled against its smaller feed screw so the cuts were not uniform.The consistency is better when the compound is rotated so that the force is against the dove tail, and the gibs are tight.2) The cross feed has a DRO, for better accuracy going into the thread depth.I have done LH and RH threads eg the bike pedals and the straight tool seems to work OKTool holder was converted a few years ago to a quickchange tool post set similar to Tautech's intended set.It saves a lot of tedious tool adjustment. With an extra holder purchase recently, the 2 most used tools ready to go.

author: tautech
author_rank: Super Contributor
timestamp: December 11, 2022, 07:17:48 pm
content: Quote from: mag_therm on December 11, 2022, 05:35:21 pmWere you backing out with the cross slide then coming back to zero then advancing the compound ?On the Harrison here the legend dials on each slide can be zeroed which makes returning to zero easy although with older worn lathes one needs return to a setting before zero and then advance to it.For threading you sometimes see operators in videos do a scratch test with tooling by working the carriage back and forth to find the work OD zero.QuoteI've come to the conclusion I'm better of to polish my tool height setting processes and if that means upgrading some tooling to help with that so be it. One of the next things to turn is a tooling tip height setting gauge I mentioned a few posts back, something like this:

author: mag_therm
author_rank: Frequent Contributor
timestamp: December 11, 2022, 07:51:17 pm
content: I leave the half nuts engaged for the whole thread cut.Just back out tool by about 0.3mm when reversing back to start.I only work in mm these days even when doing USA threads. Anyway the DRO is much easier than the scales.Also DRO is reading the actual cross slide position, and to 0.01 mmThe depth by the DRO lines up with the micrometer more closely than when using the scales.

author: tautech
author_rank: Super Contributor
timestamp: December 11, 2022, 08:06:34 pm
content: Quote from: mag_therm on December 11, 2022, 07:51:17 pmLikewise.Although watching a treading vid recently I really need learn how to properly use the pitch engage indicator if only for it to look like I know what I'm doing.

author: tautech
author_rank: Super Contributor
timestamp: December 13, 2022, 02:54:54 am
content: Bit the bullet and got this:https://www.ebay.com/itm/28500711188625mm shank tool holder plus 10x 60othreading inserts.Arrives early in the new year.

author: Benta
author_rank: Super Contributor
timestamp: December 13, 2022, 10:28:10 pm
content: Looking at Harrison 12 pics, 25 mm seems a bit over the top, looks more like 16...20 mm to me. I'm judging by the four-way tool post and the width of the slot base supporting the holder.But up to you.

author: tautech
author_rank: Super Contributor
timestamp: December 13, 2022, 11:53:38 pm
content: Quote from: Benta on December 13, 2022, 10:28:10 pmYes, OEM tool post was too small for most of my tooling and I already had this larger tool post and nut that required minimal modification to fit. Will post up a pic of it maybe later today.Therefore I'm staying with the larger shank tools that I have a small selection of. Some have been machined thinner which creates disparities in correctly setting tool height which was driving me towards investing in a QC tool post and a good # of holders that once correctly set makes changing tools a breeze.However I can have 4 tools all correctly set but the shanks and shims need be short for tooling to be properly supported and as a lot of my work involves heavy cuts I only fit 2 tools to the tool post at one time, normally a LH and a parting tool and sometimes a boring bar instead.Started on some mods yesterday to make a custom washer to fit the tool post fastening bolt/handle for the handle to be fully tight and facing more away from the workpiece where it really should be.Turning done and only requires parting off....delayed as have been checking and adjusting gibs.Last parting job cost 2 inserts and gave up to use a 1mm cutoff wheel instead !Then onto turning the tool height setting tool....another project I need have done months ago as it will be a great time saver despite requiring some time to build it.

author: tautech
author_rank: Super Contributor
timestamp: December 14, 2022, 09:44:37 am
content: Some pics....1st a shot of my preferred 125 x 40mm slot tool post with new custom washer to tighten ~90oto the work, well outta the way !2nd the OEM 80 x slot 30mm tool post with Tee slot nut and attached pivot shaft, top nut tightened. Its spanner is a gawd awful cobbled together thing with an old socket welded to a handle affair. Never liked it and never used it as it seemed the most ugly feature of the whole lathe.Standing unsupported nearby the tungsten insert is the new tip height gauge spun up today from shafting ex an automotive power steering rod with captured ball joint (worn out) parted off early in the build.BentaDragging out the old tool post from within a deep corner in the lathe cabinet and dropping a ruler on it was quite a surprise it being the 80mm square with a 30mm slot, easily large enough to handle 25mm tooling.Although I didn't measure some old HSS tool holders here it was plainly obvious they wouldn't fit in the OEM tool post but do in this other 125 x 40 beast so probably measure 1 1/4"(~32mm)

author: tautech
author_rank: Super Contributor
timestamp: December 23, 2022, 09:59:34 am
content: 10-12 days to Auckland from China never ceases to amaze me for just parcel post !Anyways the new 25mm shank threading tool and a 10pk of 16mm turning inserts arrived and while waiting the lathe got exposed from under several 20L buckets of swarf and 2 tip height tools made to assist with setting tip to center heights.Not used in anger yet but hopefully soon some trial cuts to get the feel of threading with carbide using single and multipoint techniques.

author: Bigfoot
author_rank: Contributor
timestamp: January 02, 2023, 10:07:36 pm
content: I notice you're using a negative rake insert and these require quite substantial rigidity in both spindle and cross slide arrangements on your lathe as well as a multi-horse power drive. That is if you are aiming for a good finish. Now I'm not sure if you realize these inserts come with a specific cutting edge radius which is your minimum depth of cut or infeed. These inserts peel rather than shear hence the need for the rigidity and horse power. Negative rake tooling is not always a good thing on a common home workshop type machine . You can get inserts for aluminium which have a sharp edge not a radiused edge and they work on many common alloys not just aluminium with caveats. Keep in mind that most insert tooling is very brittle , a sharp edge does not survive long under load. This is why the cutting edge is radiused so that micro fracturing is minimized and tool life is extended.Insert threading tips also come in variants for specific thread pitches that is the tip radius depends on the thread pitch so 0.5mm pitch is a different tip than 1mm. These tips always produce a rounded thread root proportional to the pitch and this can be a source of chatter.Brazed tip tooling is quite different, you can buy these and probably mainly targeted at the hobby market. You can make these yourself and grind according to your needs.I recommend CoHSS (Cobalt High Speed Steel) it's harder than standard HSS and performs similar to TC but not exactly. It's great for threading and machining tough alloys like 4140 steel. It doesn't like intermittent cuts or shock loads as it fractures at the cutting edge just like TC or ceramic inserts. Also bear in mind that common HSS coming out of China is a softer alloy than what we normally call HSS, it requires constant resharpening.On a home workshop lathe it's common practice to use the set-over method for threading that is to set the compound to just under half the thread angle and feed in with the compound so the tool is cutting only on the leading edge. Another method particularly for tough alloys is to advance the compound (not set over) a thou or two ( 25micron) every other pass to reduce the tip load which increases geometrically as feed increases. The final pass in both methods is plunged to clean up the trailing edge. The basic method is the straight plunge , OK for fine pitches and soft alloys . If you're lathe is flimsy or worn out you would need to implement the set over method regardless of the cutting tool technology.In the olden days we used to be able to buy leaded steel with the designation 12L14. This was called screw rod in several markets for obvious reasons. It was the preferred alloy for making screws , nuts and bolts on automatic screw lathes. It cuts like brass and takes a mirror finish with ease. Mild steel these days is a broad range of alloys with minimal carbon and no lead but gives a ragged finish when turning and threading on small lathes. In the industrial workshops and factories modern machines can achieve a mirror finish in 4140 steel using those very inserts you are using but under highly controlled conditions. I would not expect exceptional finishes with insert tooling on an old small lathe.I would be using insert tooling for tough alloys and iron castings which the later I use a brazed tip tool to remove the skin in as few passes as possible then change to CoHSS for near mirror finish. I generally thread with HSS no top rake i.e. zero rake and sometimes if not feeling lazy I will use a retracting screw cutting tool holder in a QCTP to minimise adjusting the infeed. I often cut ACME threads, the most recent 7/8"x5TPI 3ft long. The smallest thread I have cut is 0.4mm x0.1mm pitch on a watchmakers lathe for making a tap in silver steel. For difficult or challenging pitches I cut them on a CNC lathe at 2000rpm where I can specify the pitch , half angle infeed (simulated set over) number of passes , depth of each pass and the number of final spring passes. On a manual lathe threading should be done in back gear or the lowest speed on the small chinese hobby lathes we see on the market. This will give the best finish and results.Cheers,Peter.

author: tautech
author_rank: Super Contributor
timestamp: January 02, 2023, 11:03:25 pm
content: Thanks very much Peter for sharing your knowledge.What you call the set-over method is all I've done thus far using 5/16" HSS and threads mainly 1/2" UNC but wanting to get a bit more adventurous and go to carbide.This Harrison 12 running 3hp on 3ph has no issues with heavy cuts and in the right work I'll happily take 60 thou (1.5mm) cuts with negative rake carbide or HSS although I've not pushed it any harder as dodging the purple swarf becomes an issue.I mainly turn dry or with some compound like Rocol RTD when in those awkward steels or needing to take big cuts.But as a hobbyist turner I'm still learning how hard to push things and I notice a recent rush job taking large cuts has certainly dulled a carbide to where I can't get the same nice finish so it's time to turn in another corner.....the exact reason why I so like triangular double sided inserts.

author: Bigfoot
author_rank: Contributor
timestamp: January 03, 2023, 01:31:33 am
content: With heavy cuts you may want to use some proper lubrication but it either has to be mist or flood. Carbide and ceramic wont tolerate, squirt , drip or brush as this causes shock stress. It's happy dry or constant lubed. Also keep in mind carbide has a limited life it was mainly designed for the NC machines with auto tool changers . Try checking under a microscope next time you get a dulled carbide insert. This might give clues as to cause of failure. 1/8 or 1/4" cuts shouldn't be problem rigidity might be though. Nothing wrong with pushing the envelope. The purple swarf is an indication of ideal cutting parameters. It's not nice when you get it down your boot or down the front of your shirt. There's no shame in wearing shock protectors or button up collars!To get a nice finish with HSS it's worth ensuring you have ground the right tool geometry for the material and use a hard slip stone to stroke the cutting edges to a mirror finish and also hone a small radius at the very tip of the tool. This will make a massive difference to finish even without fine feed.Coolant systems can be a real bother, that stuff is messy at best if not contained. Mist coolant can be inhaled which is not good for anyone. I mainly use soluble oil in a squirt bottle for HSS. One of my mills has a built in flood coolant system but it needs a large catch skirt fitted which increases the footprint.On small instrument lathes I use carbide almost exclusively when turning hardened carbon steel and quite often observing the cut under a microscope, you can see what's going on . Carbide produces a near mirror finish when honed correctly but any chatter will rapidly destroy the cutting edge and this also goes for full size lathes. QCTPs are not always rigid enough typically with excessive overhang since the deflection force is proportional to the 4th power of the overhang and then some of these QCTPs are not made well either particularly the piston type. Sometimes it pays to use a conventional turret toolpost especially when chatter is an issue as the tool is usually supported all the way down to the cross slide.

author: tautech
author_rank: Super Contributor
timestamp: January 03, 2023, 04:09:32 am
content: Quote from: Bigfoot on January 02, 2023, 10:07:36 pmBeen at the lathe since I replied and checked the rake on the threading insert and while the tool holder is indeed negative rake the insert has a grind for it to be just slightly positive rake which of course being carbide can't be too positive as it will be too brittle.Quote from: Bigfoot on January 03, 2023, 01:31:33 amAh, more gems, thank you !QuoteThis Harrison has a suds pump although I've never used it and somewhat reluctant to with anything water soluble as the lathe is not in constant use and might not get used for a weeks at a time and I already have my hands full keeping atop of corrosion as it's in a shed and subject to Auckland extremes of temp which are certainly nothing bad but the humidity can be and I've seen it totally covered in a wet dew.I'm hoping that better tooling and cleaner cuts can help keep the lathe cleaner although some of the turning stock I have can only be called rusty old shit so a heavy first cut is called for to get under the rust in a single pass and it might just be I need keep atop of cleanliness and lube to keep the rust bunnies at bay.If you have any suds recommendations I'm all ears..

author: nctnico
author_rank: Super Contributor
timestamp: January 03, 2023, 05:42:52 am
content: I use thick oil (for use in a car engine) to put a protective film on my metal working machines that are in cold shed as well. It works quite good to prevent excessive rust. Doesn't look that pretty like your Harrison, but where there is oil/grease, there won't be rust.

author: Bigfoot
author_rank: Contributor
timestamp: January 03, 2023, 06:32:31 am
content: Traditional suds is soluble oil. We used to get this in cans to put in the car radiator but can be bought at places like Hare and Forbes if they are in NZ. A good machinery dealer should stock something like Garrick. I don't have a problem with soluble oil causing corrosion but it can get infected with metal eating bacteria and also cause dermatitis. Most industrial grade cutting oils stink and are not friendly to humans or the environment. I suggest a Rocol cutting oil , they do make it, can't remember the name at the moment. If you are machining Aluminium then Low Odor kerosene brushed on is excellent followed by WD40 as second choice. This is not coolant but merely a cutting lubricant and will smoke excessively if the chips are hot.If you've done much Aluminium machining you'll know it welds to your cutting tools without a lubricant and will destroy carbide quickly. The alloys used for enclosures is I believe high in zinc and throws chips rather than ribbons and machines nicely. There are certain alloys designed for machining and extruding.With carbide inserts unless razor sharp are designed to peel and rub as mentioned previously hence the need to use a lubricating cutting oil under heavy loads.A good oil to use for protecting exposed metal on a machine is chainsaw bar and chain oil. This is thick and designed to stay put and will not disperse readily . It's actually quite sticky stuff and not expensive. There is Shell Ensis if they still make it which was designed for that purpose. I have some proper slideway oil , could be Ensis but it's similar in consistency to bar and chain oil. WD40 has become unpopular for anything other than removing chewing gum but CRC seems to work well for protecting metal so if you use soluble oil you can always spray your machine down with CRC to disperse it but what I see is the water seems to evaporate out of the soluble oil leaving the oil behind.I don't have a huge problem with rust in my workshop but cold machines are always at risk especially if fog rolls in or you get the spurious warm humid day when the machines are colder than ambient temperature. Some people in cold climates keep a low wattage incandescent light under the machine to heat it above ambient.The double sided triangular inserts are a good thing for economy sake. You should expect them to last for the duration of the job or hours of turning before dulling. This would be a serious issue in the CNC world if they didn't. I

author: nctnico
author_rank: Super Contributor
timestamp: January 03, 2023, 06:40:31 am
content: For drilling/ milling Aluminium, I use Relton A9 as a lubricant. Works like a charm.

author: tautech
author_rank: Super Contributor
timestamp: January 03, 2023, 08:58:51 am
content: I'm starting to see the sense in different cutting aids and understanding the tooling shocks of the brush or occasional squirt compared to a continuous flow so I'm tempted to splash out and get a 5L of Rocol RTD Liquid that you can use neat/undiluted which should also give amazing rust protection.https://nzsafetyblackwoods.co.nz/en/rocol-rtd-liquid-5l-each--04383406Another alternative might be 35:1 Rocol but not thinned with water but some non/low flammable solvent.....but just what ? Washbath fluid ?https://nzsafetyblackwoods.co.nz/en/rocol-35-1-longlife-soluble-oil-4l-each--07741858Whatever I decide for suds I also need some good ol' RTD for all the normal drilling/tapping etchttps://nzsafetyblackwoods.co.nz/en/rocol-rtd-compound-500gm-tin-each--04461700Recommended for this 1970 Harrison slideways and throughout gearcases is Shell TonnaT 68 however for hobbyist use where the lathe is not getting hot or even warm a 32 weight is generally recommended on the Harrison lathe forum.Further investigations shows a TonnaT 32 crosses well with an ordinary 32 weight mineral hydraulic oil which is what I'm using currently but for slideways protection certainly a chain bar oil with its anti throw/stick properties would be an excellent Autumn/Winter protection solution and I use saws enough to always have a 20L on hand.Never turned much alloy however I have worked a bit with magnesium alloys like used in saw crankcases which is amazing stuff to machine, drill and tap but never done enough in one batch so see it have an effect on tooling.Tricky shit to weld but easier with TIG than oxy.Now Water Displacement formula 40 has no place in our workshop as we prefer more useful preparations.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 03, 2023, 10:17:39 am
content: The machine shop at our institution moved from flood lubrication/cutting to mist that was directed right where the cutting took place. It was a lot less messy.

author: tautech
author_rank: Super Contributor
timestamp: January 03, 2023, 10:28:08 am
content: Yes spotted this that Rocol call their Accu-lube range amongst their cutting fluids:https://www.rocol.com/productsStill I'm not sure I want to work where there's a cutting compound mist, non toxic or not.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 03, 2023, 02:26:21 pm
content: From my experience in that machine shop, there was no more odor from misting than from flood cooling. It doesn't take much mist. It is not like using a vaporizer in your home.

author: Ian.M
author_rank: Super Contributor
timestamp: January 03, 2023, 03:02:10 pm
content: You can get away with manually applied cutting compound/oil with insert tooling as long as you apply it evenly before starting the cut. Once the tool touches the work, it heats up and you cant add any more without risking thermal shock damage, till the cut has stopped and the tool has cooled. Also, because it has to be viscous enough to stay on the surface, and the tool is cuttingunderthe existing surface, very little of it gets to the actual cutting edge or the rubbing interface between chip and tool, so its typically considerably less effective than flood or mist coolant lubricant.

author: tautech
author_rank: Super Contributor
timestamp: January 03, 2023, 08:56:05 pm
content: Quote from: Ian.M on January 03, 2023, 03:02:10 pmYes that's exactly what I used to doQuoteThis is what I have just learned thanks to Bigfoot. So far it has only cost the the top efficiency of 1 of 6 edges on a double sided triangular insert.However I've also been having real problems parting that I'm now quite sure is due to insert thermal shock which these tiny 2mm parting inserts seem particularly susceptible to.Did I get the wrong carbide parting tool for GP work ?https://www.ebay.com/itm/282936006971?hash=item41e04cd93b:g:syMAAOSwybpboJYEQuoteRTD paste has been my cutting aid of choice for ages but instead I've been using a cheap low speed tapping paste that I've never been particularly keen on from the first moment I used it turning.

author: mushroom
author_rank: Regular Contributor
timestamp: January 04, 2023, 02:42:14 am
content: The ideal QCTP ! The best of the two worlds.Made by Tripan. Takes different toolholders, up to 25mm (series 1, 2, and 3). And if overhang is a problem, it still is a conventional turret. Seems to me it was discontinued, and is now available for one toolholder size only. On the other lathe, much smaller than this 8HP beast, I also put a Tripan QCTP that fits the smaller toolholders (series 1), but has no "square style" side. After shimming the QCTP on the small lathe, the cardridges can go on one lathe or the other without needing any adjustments.Not sure this QCTP is available worldwide, new or used... They are common on Shaublin toolmakers/clockmakers lathes.Another advantage is that toolholders are easy to make, unlike the popular Multifix style.Some folks just glue the shims under each tool. Some others attach them with electrical tape (not sure it's a great idea, never tried... I doubt the adhesive will last very long because of the oil)NEVER EVER use WD40 on a lathe or any machine tool ! Years ago I had the great idea to "protect" everything with that crap before I leave the machine unused for a couple of months. It evaporated, leaving a coat of brown waxes. Had to take the machine apart to clean it and it was a real pain. Chainsaw oil is known to be a good substitute to the classical ISO VG 64 way oil.Years ago, I read on a forum (CNC Zone ? Practical Machinist ?) that ATF oil (Dexron) had the best anticorrosion properties because of its anti oxide additives, and was the best for long time protection. The author tested many oils in extreme conditions, with pictures and documented everything... Can't retrieve the thread.I've been using mist on lathe, mill and bansaw, with a homemade system that worked well. Chronic sinusitis after a few months... Should not be used free air. But it worked well, and avoided most of chip recycling on the milling machine, in particular when side milling or machining pockets.

author: nctnico
author_rank: Super Contributor
timestamp: January 04, 2023, 05:47:00 pm
content: ATF oil sounds like really nasty stuff. I always read the MSDS sheet before using chemicals and oils to see if these may pose any harm