It’s common problem when you’re building anything with screws: this one is too long, this one is too short. While she can’t teach you how to fix the latter, [Quinn Dunki] has made herself an absolutely deluxe screw shortening jig. And while that’s cool and all, the real value here is the journey; watching over [Quinn]’s shoulders while she’s in the machine shop is always illuminating.
First off, she starts with her old jig, which frankly makes us want one. It’s a short piece of aluminum angle stock with threaded holes in it. You thread the screw in as far as you want, and use the edge as a cutting guide. Very nice!
But aluminum threads wear out quickly so it works if you’re shortening dozens of screws, but gets wonky when you need to cut hundreds. The new jig is made out of steel, and has a slit that clamps the threads in place so she doesn’t have to hold the tiny screws with her other hand while sawing.
This video is, on the surface, about making an improved tool out of steel. But it’s the tips along the way that make it worth your watch. For instance “deburr early and often” is a recurring leitmotif here: it keeps the extra bits that form along any cut from messing up edge finding or vise registration. And yeah, she deburrs after every operation.
There are mistakes, and lessons learned along the way. We’re not going to spoil it all. But in the end, it’s a sweet tool that we’ve never seen before.
If you haven’t read [Quinn]’s series on machine tools that she wrote for us, it’s a treasure trove of machining wisdom.
Huh. Usually I just hold screws in the vise by the waste end when I’m cutting them to length.
With her jig, or common bolt shorteners, too, the fact that you have to unscrew the hacked bolt helps clean up the threads where the hacking happened.
She addresses this in the video though, and says it doesn’t clean up the threads enough for her liking. That being the case, I don’t see why a vise with a depth stop wouldn’t do the job just as well as her jig.
Put a nut on the screw close to the head before lopping off the end.
Removing the nut after shortening helps to clean the threads from the cut end.
She mentions this in the video. Specifically something like “in the comments you are going to say ‘put a nut on the screw'”
And proceeds to explain why that’s … suboptimal
Honestly I just chuck the waste end in a drill and rotate it while I cut with a dremel or an angle grinder
why not just use the screw cutter in your wire strippers? #6, #8 and #10 cutters are common, and are almost always the size im using
https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fimages.toolsid.com%2Fklein-tools%2Fitems%2F11055-10.jpg&f=1&nofb=1&ipt=cc6531ea348c3a976e09f10159060d36d39614f0ecb1ceb58f755c62ca00464b&ipo=images
Surely those are for copper and brass electrical screws and won’t hold up to steel and stainless
They do if: 1) you got a good quality pair of wire strippers 2) you use it to cut bolts with a grade of 8.8 and less (don’t know the equivalent in ex-world police units :D )
I have a good quality pair of wire strippers and I use the screw cutter for stainless steel screws all the time. Works perfectly up the 10-32. If I’m going to thread the screw into aluminum or plastic I do touch up the end of the screw with a file to make sure there aren’t any burrs.
I even bought a second pair of metric wire strippers specifically to cut metric screws.
She made this specifically for brass screws.
She addresses this in the video. Any means of shearing the threads off deforms them. Good enough to nip down an 8/32 or 6/32 for a cover plate, but if you’re doing hundreds of them at machinist precision tolerances it’s not good enough.
If you need to cut hundreds using machine tool precision tolerance i suggest buying a box full of the correct size
!!!!! amen
i kept trying to understand the motivation for this and you put the nail on the head
Might be a different HaD project.
… put the screw in the hole…
A lot of the smaller sizes are not available in the shorter lengths a modelmaker might need. Once again, addressed in the video. Don’t think you can out-think her on the subject especially with something so obvious.
Oh well… I didn’t realize that her solution was the definitive, end all and be all for every single situation. Do we all just bow down at once or do we line up and do it collectively š
Ok Derek, If you’ve got a better design, let’s see it. Regardless, show some respect.
My condescension wasn’t aimed at her. It was aimed at you. Your “there is no way that you , a commoner, can possibly out-think our queen” rhetoric is arrogant.
I think you have mixed up your bookmarks for hackaday.com and justbuyexactlywhatyouneed.com
JBEWYN.com is awesome. They have everything.
Except every damn thing seems to be out of stock.
Some people don’t have the desire, or time to waste making things when they can just be bought. The solution in the OP is fine for small volume jobs but suboptimal for anything of substantial volume. Buying is optimal though.
I have tried that many many times, it just flat out isn’t possible much of the time. To the point I generally don’t bother buying premade screws at all, for the small stuff – the turning and thread cutting keeps some practice on the lathe and doesn’t take that long, probably generates less waste too as those small diameter screws tend to be sold only in really quite long lengths.
Ewwwwww SAE screws š¤®
BlondiHacks and HaD overlapping seems about right. Didn’t know she wrote some articles for HaD and will read all of them with joy.
She is the best.
If you need to shorten hundreds of screws you could just buy a box of the correct length.
+1
Also explained in the video. They come as standard length and many/most model engineering projects need custom length.
Else if you have to make them it’s easier to make long ones then keep them around and trim to length as needed
If you’re cutting down hundreds of screws, you did your design work wrong.
You’re making the following assumptions, all of which are incorrect.
1) All the fasteners this tool will modify will used in one project, when it actually looks like the perfect toolbox companion.
2) All projects have a neat Design – Make – Use flow. Rarely the case, especially for smaller projects.
3) The design work was perfect and nothing was discovered during the project requiring changes. Never the case (for me, at least).
4) Fastener length is within the control of the maker. Rarely the case when modifying or restoring.
5) The time to order everything needed is available. Rarely the case.
6) The budget needed to order everything is available. I wish budget were never an issue, but I’m yet to do a project where it isn’t
This is addressed in the video, a full 90 seconds in. She’s building a scale live-steam locomotive which requires tiny screws of all different lengths, but those screws are only sold in size “long”.
I needed a 19mm machine screw when I had a 20mm. Drilled a hole in a wooden block, put the screw in, sawed off the excess mm with a hacksaw. Picked up the sliver that fell off. I can still see the burn mark on my finger two days later.
I have cut down hundreds of screws, bolts, even nuts, and then also scratch built hundreds of bolts ,screws, and nuts, all by hand, in lots of 1
to 16 max.
The jig shown is awsome, but I need 6 for “all” the sizes.
the missing part, cutting a threaded fastener and leaveing just one start thread, is hard
so I always just fix it with a file, which is, easy.
I supose if a person got right into it, a collet vice and a v block set up would grab all the sizes, and would work for drilling pin holes, and other
holes in round stock, so might be worth the effort
hmmmmm, got a whole bunch of off cuts that would work for the leaves
Dremel with a cutting wheel.
That’s a bolt. If you cut off a screw, you lose the tapered point, thereby creating a bolt. Unless it’s the rake of the helical incline that makes a bolt and not the tapered point. Hmm….
Yeah I was hoping for a self tapping/wood screw shortening guide but this is just for threaded bolts, should clarify the title with “machine screws” since just “screws” implies the more common wood or self tapping kind.
Again between material thickness choices and additional counter sunk depth you should never need to use anything but off the shelf bolt sizes if for no other reason than to be kind to the poor sod replacing a rusted bolt on your project 10 years later and finding out it isn’t 16mm but was 13.5mm and now the threads are all chewed out or they use 12mm and now it only has the tiniest engagement liable to pop off from a stiff breeze.
It’s a bolt if you use it with a nut. It’s a screw if it goes directly into the workpiece.
With all due respect, both of you are incorrect… It is a bolt if the tool that you use to adjust the fastener’s head is a wrench (gripping the exterior of the faster head. It is a screw if you use a screw driver to turn the fastener. The difference in as simple as a belly button. If it’s an “innie” then it’s a screw. If it’s an “outie” then it’s a bolt.
While I am at it, when you garbage up the threads on the fastener such that you cannot tighten it anymore, it is correct to say it is stripped. When the head is garbage such that you cannot turn it using your wrench or screw driver, the fastener is cammed. These conditions are usually avoidable with the correct discipline, but some people live where salt is used on the road. So don’t make a bolt too long, don’t make a fastener whose head is pointing toward the ground, or opposing the direction of travel. The reason is that water can properly drain in these configurations without trapping as much debris.
https://www.homedepot.com/p/Crown-Bolt-6-32-x-1-2-in-Phillips-Hex-Head-Machine-Screws-8-Pack-42681/203496357 What does that make a combo Phillips/hex head? A scolt? A brew?
ASME and Machinery’s both use the nut vs threaded workpiece definition. Is there a different standard out there (ISO? DIN?) that defines it based on the head type?
Klein strippers will last through at least five years of cutting number 6 and 8 screws every day without any need to refine thread. If you are in the unfortunate position of cutting 4-40 screws for a series of backplanes, I have an outstanding trick taught to me twenty years ago during my apprenticeship. Take a fine blade hacksaw. Turn it upside down, so the blade is up. Put the end of the hacksaw in a door strike plate to hold it steady, or in a mortar joint if the doors aren’t installed yet. Put the handle side in the notch of your hip. Lightly draw the bolt back and forth across the blade, letting just the weight of your hands push the bolt against the blade. This cuts an incredibly smooth cut, no filing needed even with 40 threads per inch, and cuts even 10mm thick bolts far quicker than you would think. Beats walking down to the van for a vise and a bandsaw
Having watched the video, I’m not claiming my method is better than what Quinn is doing, but not having a full machine shop available, I do what I can.
I put two nuts onto the bolt I want to shorten, and lock them together at the spot that I want to make the cut. I then put the waste end into a drill, such that there is a small gap between the chuck and the nut, where I will make the cut. I then run the drill, and place the hacksaw blade against the nut and press gently against the bolt, such that the turning drill is doing most of the work. I do also move the blade back and forwards to prevent uneven wear on the saw blade.
As mentioned by others, removing the nuts does help to straighten the burr (not “clean up the thread”, as Quinn points out), and a gentle filing can finish the job if needed.
She has created the right tool for the job. She’s creating a locomotive and all the bolts are in size miniature. What she’s doing doesn’t apply to the “huge” M6 bolts. This is all tiny stuff. I’ve been following this project from the start and she’s showing off all her mistakes, which I like as you can learn from that. I’m making motorcycle headers and I’ve made so many mistakes on that tiny project. It’s especially difficult considering I’m not buying new tubes but cut up old tubes I had laying around. It’s something that helps you learn. Same with her projects. It’s great to see how she fails upwards and ends up with something amazing. I’m really jelous of her die filer. That’s a machine that’s on my dream list, but I don’t have the tools to build one and buying it isn’t really possible as everything comes in casting kits that you have to machine.
This is a pretty nice tool, but a lot of machining for little gain (except YouTube views). Why not just use a normal strip of metal? Instead of all this belt business just drill two holes and put some dowels in.
As someone that mostly make things with M2, M2.5, M3 and M4, and the occasional M1.6 and finer, yeah, it’s always annoying to shorten screws, and I have a very good selection in length, screw heads, material and colours and try to design around that, but sometimes you need the odd size that isn’t easily available. Just like she quickly mentions there are negatives with any method you choose (and shears are the worst due to deformation), and I prefer files and dremel cut-off.
That looks like a fine tool, and I get the feeling she will wish she had made that years ago.
Both deburring & chamfering of cut of thread goes very well with a belt grinder. Make sure to grind the burrs radially towards the center of the screw (I.e., away from the thread). This ensures any remaining burrs are harmless.
But not everybody has a belt grinder. You can also put an angle grinder with a flap disc in a vise or some other kind of holder to make it stationary. Both belt grinders and flap discs are somewhere in between grinding and polishing. As a result these create much fewer burrs then a grinding stone.