fascinating way to find center point of shaft - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: March 03, 2022, 07:43:50 am
content: In this video, he finds the center point of a shaft by putting it into a drill press and pressing it into sand paper. Since this make concentric circles, I guess you can optically find the center point with good? accuracy.It's not like a substitute for a lathe, but I can see this helping some people out a fair bit.

author: Gyro
author_rank: Super Contributor
timestamp: March 03, 2022, 10:33:47 am
content: Isn't that going to give you the centre of rotation rather than the centre of the shaft? If the shaft is bent or there is runnout on the chuck then the centre of rotation wont match. Pressing the shaft into the sandpaper will probably exaggerate runnout and shaft flex because it doesn't have a centre point to locate it (as with a drill bit) so it will tend to 'shuffle'.The best bet is to hold asmallpiece of sandpaper in your hand and bring it up to the end of the shaft so that the softness of your finger will cause it the wrap slightly up the sides. This, combined with the flexibility in your finger, will make it follow the end of the shaft. Note: Make sure that the end of the shaft isn't burred / sharp (and capable of cutting through the sandpaper into your finger) and that your finger will get hot!

author: jpanhalt
author_rank: Super Contributor
timestamp: March 03, 2022, 10:37:55 am
content: What do you do if you want the center of 2" dowel and don't have a chuck that big? That is, it's an obvious method but with very limited application.

author: Ian.M
author_rank: Super Contributor
timestamp: March 03, 2022, 11:00:11 am
content: The guy is a hack!At 1:40 to 2:10 you can see him hammering on the output shaft to extract the bearing and to extract the shaft from the bearing. No attempt was made to protect the bearing againstbrinellingso that bearing is definitely compromised.Also, I don't like the interference fit of the old shaft stub to the new motor shaft (8:44 to 8:54). That should have been either bonded with Loctite 503 or similar, or a shrink fit or drilled and tapped for a grub screw and counterdrilled for balance.

author: thm_w
author_rank: Super Contributor
timestamp: March 03, 2022, 10:29:01 pm
content: Quote from: Ian.M on March 03, 2022, 11:00:11 amHard to know if he replaced the bearings or not.He did use a wooden mallet, if it were anything other than an old hand drill, maybe I'd be concerned.

author: Benta
author_rank: Super Contributor
timestamp: March 03, 2022, 10:54:50 pm
content: That's so fake.His "threads" for the battery holder made with a power tool? Even in the video you can see that they are ruined/smooth.And his "sandpaper center finding"? That's made with a lathe. You clearly see the small dimple in the middle from parting off.This guy is just a... von Münchhausen?

author: thm_w
author_rank: Super Contributor
timestamp: March 03, 2022, 11:45:31 pm
content: Quote from: Benta on March 03, 2022, 10:54:50 pmThink its a bit of an optical illusion. Also relative speed in the center of the rod will be lower, you'd expect less wear there.A drill press is basically a really shitty lathe so I can't see why it wouldn't work.

author: coppercone2
author_rank: Super Contributor
timestamp: March 04, 2022, 12:10:23 am
content: that migth be a good use for a optical center punch (but mr pete on youtube reviewed them, and its not like optical is gonna get you perfect (he got 0.005 accuracy between pins made with optical center punch), but it is ALOT cheaper and way more portable.I do suppose it would be possible to put a lathe chuck on a drill press if you get the right taper for slow marking with sand paper if you want to go to 4 inches, maybe.As for the channel, I think its impressive that he actually got that stuff to work. He also does a battery powered angle grinder this way, and actually cuts some square tube with it... yes.. its developing world quality stuff but its interesting, it looks quite professional if you believe it can be made that way with the materials he had.. modern day "african queen" (if you don't know, its a movie with people stuck in the african wilderness for a good portion of it)1 hour 3 minutes in the macguyver starts

author: Stray Electron
author_rank: Super Contributor
timestamp: March 04, 2022, 12:47:45 am
content: [quote author=coppercone2 link=topic=314941.msg4042129#msg4042129I do suppose it would be possible to put a lathe chuck on a drill press if you get the right taper for slow marking with sand paper if you want to go to 4 inches, maybe.The real problem with a drill press is that (1) it's bearings aren't nearly as precision as those used in milling machines and lathes so it's spindle will have a lot more run out than on the other two machines and (2) a drill press not meant to handle any side loads so the entire column will flex more than the column of a milling machine or the headstock of a lathe.If a drill press worked adequately as a milling machine or a lathe then they won't be making and selling those.Morse tapers, particularly the #2 MT, are commonly used in all three machines although lathes generally have a much larger chuck since they are usually intended to hold the work piece instead of the tool.

author: elekorsi
author_rank: Regular Contributor
timestamp: March 06, 2022, 08:56:42 am
content: Quote from: Benta on March 03, 2022, 10:54:50 pmWell, there is nothing wrong with power tool being used for taping threads. I almost daily do it with the acu drill for threads up to M8, also steel is not a problem. I tap an M3 or M8 without problems, resulting in perfect thread. It can be a bit problematic for deep threads, but to around 1 - 1,5D of depth there is no problems.All you need is a good tap drill (not the cheap one from the 20€ set, those in sets are good only for occasional thread repair), steady hand and good cutting oil. I cut M3 and M4 in the higher gear, M5-M8 in the lower one

author: coppercone2
author_rank: Super Contributor
timestamp: March 06, 2022, 07:14:07 pm
content: there are tap purists that only do it by hand (with frequent tap reversal) but I think in the last 10? years the tooling for power tapping has gotten more popular and better (I think it has to do with the CNC tool changer proliferating taps, they setup the grinding machines for the power taps and now they got ALOT cheaper and they figured some stuff out). Spiral point tap drills that actually have a OK reputation is pretty wild IMO.I do it manually because its what I have and it works well. Yeah we have some drastically improved product quality because they can power tap holes in stuff cheap now, so thankfully there are less rivets around. You know that the screw holes on things we like might be replaced with rivet holes if they did not figure out how to do cheap power tapping, yay for repair.It might actually be now that a power tool tap set is a viable choice for a novice looking to get into threading... but I still prefer manual because broken taps fucking SUCK.