# Cutting lots of M3 threaded rod - 15mm to 30mm long



## rwillett (26 Feb 2022)

Hi,

I'm building a number of 3d printed designs for telescopes. These are tube rings and mounting plates.

Whilst I can buy M3 grub screws and knurled knobs, I would prefer to make them as then they match the design of the printed stuff, they can be printed larger so that at night they are easier to use and the cost of them in the UK is too high (IMO). Even Alibaba is too high and I have different designs I want to use, smaller, larger etc.












Making the knobs is easy, addign the brass insert is easy, a soldering iron, a dedciated adaptor and a Dremel drill works well.

However cutting the M3 threaded rod is a pain, the dremel colours the rod, and its difficult to get a decent finish. 

So is there an easy way to cut M3 into lengths of 20-30mm quickly and easy without it costing the earth. I have seen cutters at £400 which is far too high, I have seen manual guilatines as well for £60 which might do the job.

Any help welcomed and if there are any astronomers looking to mount Raspberry PI's, Pegasus power boxes and Telrads, get in touch.

Thanks

Rob


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## Sandyn (26 Feb 2022)

I would change the design of the knob, so you can use off the shelf M3 screws of the appropriate length. Still use the insert, but fit the screw from the other end.


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## clogs (26 Feb 2022)

I'm always cutting up length of threaded rod right up to 30 mm disband there’s no easy clean way.
if u get lucky just maybe able buy ready made studs but quantities may be high..
most of the time I use a jig on a metal lathe to set length and cut off
but on sizes below 6mm it’s all a bit delicate….


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## Lorenzl (26 Feb 2022)

I have screwed the rod through a metal plate; fixed it with a nut then hacksawed it. That keeps the end nice and square and if you want you can screw it through a bit further and file the end. The aluminium may also act as a heatsink for the Dremel; stopping the end from burning?

You could change your 3D print design and have the knob push onto the head of a socket cap head screw. I have used these from RS that you could base your design on: RS PRO Black Knurled Clamping Knob, M6 | RS Components (rs-online.com)


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## AES (26 Feb 2022)

rwillett said:


> Hi,
> 
> I'm building a number of 3d printed designs for telescopes. These are tube rings and mounting plates.
> 
> ...




Hacksaw? If it's only 3 mm dia rods, then suggest 32 TPI blade. Will undoubtedly need a bit of practice if you're a newbie, but once you've got the knack (see my sticky post re Hacksaws & Hack Sawing at top of this section if in doubt) you'll find it easy-peasy, v quick, and cheap as chips! What more could one ask for.


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## MusicMan (26 Feb 2022)

Do you have a lathe? A parting tool in a collet chuck is the best way. Use the tailstock to set a stop for the rod, pull the rod through till it touches the tailstock centre, use a parting tool in a fixed position.

But I think Lorenzi's suggestion of using a push fit cap onto a socket screw is by far the best.


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## Trainee neophyte (26 Feb 2022)

A reciprocating saw with a metal cutting blade works for me. It needs a quick tidy up with a file afterwards, but clean enough.


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## flh801978 (26 Feb 2022)

A pair of CK combi side cutters have thread cutters ( for 3.5mm and 4mm ) built in and work well and not too pricey.they will shear m3 easily and with little cleaning up needed
Ian


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## RichardG (26 Feb 2022)

I have a crimp tool which incorporate a shear cutter for M2/2/5/3. One side is threaded so you screw the thread in, squeeze the handles to cut then unscrew which cleans up any deformed threads.


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## RichardG (26 Feb 2022)

Forgot my comment, I just found the pair I have online and they're only rated for brass/copper although I have cut steel with mine but...

Crimping Pliers


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## AES (26 Feb 2022)

flh801978 said:


> A pair of CK combi side cutters have thread cutters ( for 3.5mm and 4mm ) built in and work well and not too pricey.they will shear m3 easily and with little cleaning up needed
> Ian



Yeah, "OK" but if you're going to do that (IF your pliers are decent quality) I'd strongly recommend placing a nut(s) at the cutting area so that when cut (also should be easy-peasy) as you unscrew the nut off the threaded rod, it will clear deformation of the thread where the cut took place. (Same principal as a nut plate, which we all made as apprentiii).


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## TRITON (26 Feb 2022)

I bought one of these after making a complete and utter bottom of cutting some brass tubing at 30mm lengths. After struggling to get them square and true and failing totally each time, i bought the stand It was like it had been sent by heaven and made the job a breeze.
I was a bit skeptical at first given how cheap it was, but after attaching the grinder, setting it up square using an engineers square and a ruler, it was surprisingly accurate.
Where cutting each piece of brass freehand with a hacksaw took several minutes, cutting them via this stand each one was cut in under 20 seconds, to a much better finish.
I've also used it for cutting threaded rod to epoxy into wooden chair feet. Today I think its one of the handiest things Ive ever bought.
Cost only £19.99 inc postage.


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## rwillett (26 Feb 2022)

Thanks for all the replies. It seems that there's no obvious and easy answer to using M3 threaded rod. I don't have a lathe, the CFO would have a fit if a lathe turned (no pun intended) up.

I had thought about the hex headed bolts and dismissed them as I didn't like the idea of a cap to hide the hex end. However whilst walking the dog, I came up with a better idea to make it look decent. The bolt comes through the underside of the knob and there is a little plastic cap to fit inside. All of the gubbins is hidden 

I kept thinking the M3 bolt would come from the top. This looks like the RS Components principle (I think).

It's easy to print, looks nice (just done one) and is quite cheap to make. So no cutting of M3 threaded rods but I do need to buy a wide selection of Hex headed M3 bolts.


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## Lorenzl (26 Feb 2022)

I think you are still over complicating it.





The RS principle is you put the cap over the socket cap head and squeeze it onto the head in a vice. No need for brass inserts or plastic caps. You could also add a dob of glue if you wanted belt and braces job

Also on your image you have a hexagonal hole but you want a round one?


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## Marischal Ellis (26 Feb 2022)

Screwed rod comes in long length...must be 20ft. or so. Any help. Heating engineers use rod for hanging 'things' may be a poss. Haven't looked at finer details you may need. It is only 3mm.


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## rwillett (26 Feb 2022)

Lorenzl said:


> I think you are still over complicating it.
> View attachment 130410
> 
> 
> ...



The hex hole is correct as the bolt will go into the bottom, there is then a hex plug to seal it up and make it look pretty (ahhh). I've ordered a lof of M3 hex bolts and will try them out.

Thanks

Rob


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