Torque limited screwdrivers - Page 1
Forum section: electronics / general

author: tszaboo
author_rank: Super Contributor
timestamp: April 07, 2024, 11:08:12 am
content: I have a set of Wera 7400 series torque limited screw drivers at work. It's a set of 3 hex drivers which can be set up between 0.3 and 6 Nm. Wera 05074739001I have now a bit of obsession with this, as it is very nice/satisfying to be able to assemble something without the fear of ripping screws. And it's good for R&D when you need to be able to tell production what torques to use when assembling something. For example I run into several occasions, when an enclosure assembled with a certain torque was fulfilling it's IP rating, but not below, or above that. And I want to be able to do this at home as well. The set is about 250 EUR, which is a bit too much for my liking.So this is a topic about torque limited screwdrivers.Share your experience!

author: TERRA Operative
author_rank: Super Contributor
timestamp: April 07, 2024, 11:43:33 am
content: I have a CDI brand 401NSM-CDI torque screwdriver that I don't use as much as I should...It's great when I do use it. Most often for torquing components down to heat sinks to make sure they are tight enough without stressing the component.I also picked up a Tone brand TBS20 'Torque Bit Ratchet Set' recently that I haven't used yet, but it looks pretty good.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 07, 2024, 12:03:52 pm
content: I hate non-answers to questions posted on blogs, but maybe my experience is slightly relevant. I like the idea of a torque measuring screwdriver and have often considered buying one. For home use, there are a lot less expensive torque-indicating drivers available, and modern digital versions are very attractive. I just haven't pulled the trigger yet. I do have experience with torque wrenches and currently have 5 dating over generations to the 1960's. My oldest are Craftsman, made in USA, and torque bar indicating.Torque limited v. torque indicating: I worked with a considerably older and experienced AI mechanic in the 70's and 80's on civilian aircraft. He would not allow a click-type torque limiting wrench on critical components, which included spark plugs. However, there is no argument that clicker wrenches are easier to use particularly when working in limited space and difficult visibility. That is what I usually use today on my car and implements. I always use torque indicating on spark plugs and other things screwed into aluminum heads.With respect to my hobby electronics and home, the biggest problem is with coarse threaded, "thread forming" screws in soft materials like plastic, aluminum, and sheet metal. The risk of cross threading and destroying existing threads is high. Do that a few times, and there are no more threads. The best solution is to turn the fastener backwards until you just feel a little click or give, then proceed to turn in the correct direction, which is usually clockwise. That first turn is critical, and if there is more than the usual low resistance, repeat the procedure to find the correct thread start. A dedicated screwdriver (i.e., one without removable bits) is best for feel, but not required. Final torque is up to you. For home use, snug or just a little beyond it is all I do. In sheet metal, too loose a fastener can allow the screw to get slightly cross-threaded and needs to be avoided.

author: tszaboo
author_rank: Super Contributor
timestamp: April 07, 2024, 01:26:22 pm
content: Quote from: jpanhalt on April 07, 2024, 12:03:52 pmFor wrench, maybe. For a 1/4in hex screwdriver, I don't see how the limit vs indicator would make a difference. We are dealing with 1/10th the torque on these screws, instead of bolts. It's very different. The Wera doesn't actually click, it skips and turns 1/6th maybe 1/4th when the preset torque is reached.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 07, 2024, 03:09:23 pm
content: In terms of accuracy for small fasteners in non-critical applications, there is probably not much difference between and indicator and limit torque tool.However, I prefer a gauge to idiot lights almost without exception when I can see the gauge. In all instances, I still go by feel regardless of whether it is a spark plug or mounting screw for a PCB. The indicator/gauge is confirmation and backup. For non-critical items, when it feels right, I usually stop even if the desired torque has not been reached.

author: voltsandjolts
author_rank: Unknown
timestamp: April 07, 2024, 03:35:26 pm
content: Here is a budget option that I have and can recommend:Worx WX-242https://www.aliexpress.com/item/1005005713615349.htmlCirca £38 delivered.I think these are supposed to be China market only, so there is some mention of 'Youpin' brand there to bypass some automated restrictions, ignore that.It is very nicely built, sturdy and solid feel. Torque range setting is good, at high setting you really got to have a good grip of it, at low setting it's very mild and won't do damage to any metal screws. USB-C charging, driver bits lock securely into place (not just magnetic as some others), good LED light.

author: Zoli
author_rank: Frequent Contributor
timestamp: April 07, 2024, 04:00:17 pm
content: Quote from: tszaboo on April 07, 2024, 11:08:12 amMy experience: typically, the torque drivers have an useful range of 10(1-10Nm ex., mechanical) to 50(2-100Nm ex., digital, load cell based); this would place the Wera in the lower end with the his range of 3(I'm pretty sure it compensates elsewhere, like long term stability/reliability). Typical range for electronics:0.1Nm(M3/#4 sheet metal) to 3Nm(M5/#10 on heat sink). Multiple screws(IP rating cover): repeatability has the same(or even higher) importance then just torque rating himself(uniform distribution of the load). For home use, one or two digital with vibration would be OK, IMO; interchangeable tips(including for SMA) is strongly recommended. The best torque wrench I've worked with was a Snap-on: 4 LED bar-graph, digital display, audible and vibrating limit - but the price

author: tszaboo
author_rank: Super Contributor
timestamp: April 07, 2024, 05:06:04 pm
content: Quote from: Zoli on April 07, 2024, 04:00:17 pmThe Wera is a 1/4" bit driver, which is for Phillips and Torx screw for example. What you are talking about are wrenches.

author: Zoli
author_rank: Frequent Contributor
timestamp: April 07, 2024, 05:22:04 pm
content: Quote from: tszaboo on April 07, 2024, 05:06:04 pmEverything, except the last phrase, applies both to screwdrivers AND wrenches; sorry if I wasn't clear in the first place; if you have more questions, please ask.

author: 2N3055
author_rank: Super Contributor
timestamp: April 07, 2024, 06:47:53 pm
content: I have Wera 7440 (0,3-1,2 Nm) and Proxxon Micro-Click 5/S (1-5 Nm).They both torque limit in tightening and a not limiting in unscrewing..I have a friend that is mechanical engineer and he checked them (they have torque tester) and both are holding well.Wera was better than spec.I do take good care of them and handle them gingerly.

author: tszaboo
author_rank: Super Contributor
timestamp: April 07, 2024, 10:17:10 pm
content: Quote from: Zoli on April 07, 2024, 05:22:04 pmWell you also mentioned 10-50Nm, which is for "car tires" and not for screwdrivers. The Wera is actually a set of 3 drivers covering different range, supposed to be 6% of setting accurate. Anyway, back to topic.Quote from: 2N3055 on April 07, 2024, 06:47:53 pmThat sounds very interesting. Good range, and resolution. 1-2" and 1/4" drive. I see it discounted to 30 EUR at the moment ?! Is it a good driver? How is the ergonomics?

author: 2N3055
author_rank: Super Contributor
timestamp: April 07, 2024, 10:40:57 pm
content: Quote from: tszaboo on April 07, 2024, 10:17:10 pmIt is good quality and keeps the calibration.In comparison to Wera, it is heavier, but quite robust, handle is just round (although good "meaty" diameter) and has nice anti skid surface. It is not as nice and light as Wera, but works OK in hand.It's weight and robustness is appropriate for larger torque it has.Make not that as you get to 4-5Nm you need firm grip, but that is normal.If you can get it for 30€, I recommend to buy it at once. That is excellent price you cannot go wrong.5/C is 1/4" square drive, you get locking adapter for bits.

author: Zoli
author_rank: Frequent Contributor
timestamp: April 08, 2024, 12:13:10 am
content: Quote from: tszaboo on April 07, 2024, 10:17:10 pmOne: the 1-10/2-100 Nm is mentioned as example(ex.) for span(not range, my mistake; English IS a funny language).Two: in the second phrase I'm giving the typical useful range for electronics: 0.1-5Nm.And one more clarification for my original post: when I've said load cell, I've meant strain gauge load cell; I leave the hydraulic|vibrating wire load cell based torque wrenches for the real masochistsNow enough of explanations, back to topic:My daily driver(pun intended) is aSnap-on QDriver4; it does the job, but it's fragile: if you drop it too many times on the concrete floor, it's going out of specs; OTOH, I don't think dropping would be a problem for the Wera or Proxxon

author: DiodeDipShit
author_rank: Regular Contributor
timestamp: April 08, 2024, 02:07:22 am
content: The Wera 7400 seems a great torque screwdriver, though I do not prefer that style handle.I have been using a MAC Tools TSM2-36 Torque Screwdriver for many years. I borrowed it permanently when I retired from my Aerospace job. It may be the standard in quality and accuracy. I highly recommend this screwdriver.However, after I bought a cordless Millwaukee M4™ 1/4" Hex Torque Screwdriver, O Nm - 5 Nm , I hardly use the old MAC anymore.https://www.milwaukeetool.com/products/2101-22

author: tszaboo
author_rank: Super Contributor
timestamp: April 08, 2024, 03:45:30 pm
content: Quote from: 2N3055 on April 07, 2024, 10:40:57 pm30 EUR in stock. I click to "Buy now". It's actually not in stock for that price but you can buy at it at 80 EUR from another partner.Damn scammers.

author: JimKnopf
author_rank: Frequent Contributor
timestamp: April 12, 2024, 03:16:44 pm
content: I use this two Wiha. The bigger one is an iTorque 2835, electronic adjustable.The smaller one is manual adjustable, TorqueVario-S 2852.

author: nali
author_rank: Frequent Contributor
timestamp: April 12, 2024, 04:18:06 pm
content: Quote from: DiodeDipShit on April 08, 2024, 02:07:22 amThat M4 looks *very* similar to a Panasonic driver I had at a previous job. Great little tool, I do miss it.

author: mendip_discovery
author_rank: Super Contributor
timestamp: April 12, 2024, 06:00:17 pm
content: Standard for Torque Screwdrivers Type II class D is 6% but many are much better than that.Having decent torque stuff does save on stripping of threads especially in to plastic.Torqueleader does some useful indicating ones that you just turn and read the dial. Not as good as a click but ok.You Wera do a range of drivers in HV mode as electricians are starting to use them when doing up terminals.Always handy to find on the bay is the old torque clocks which can be used to check the drivers and also to get a feel of how to do.stuff us consistently.

author: tszaboo
author_rank: Super Contributor
timestamp: June 05, 2024, 03:07:47 pm
content: Ok, so after a bit of search and shopping, I now have a Shahe Torque limited driver (~25 EUR). The model I have can be set between 0.5 and 3 Nm, which is a good general purpose range.I've tested it on a Delta Regis torque calibrator. Measured it on 1, 2 and 3 Nm, with interesting results. So the driver has a specification of +/-6%, but I actually measured 2% on 1Nm and 1% on 2 and 3, repeatable, which is excellent. I have to see if it holds this values long term. There is a little play on the shaft, and it's not as comfortable as the Wera drivers. It also has a 6 Nm variant, you don't want to have that with this driver I think.