MicrobeHunter.com Microscopy Forum

Hello
I'm wondering if somebody knows a source for RMS thread tap and die; meaning, the machining tool that you screw in a hole and cuts the thread.

It has been a wild dream for a while, I'm fed up with 3D printed plastic, nor I have a lathe. Well, actually I'll use it mostly to "finish" 3D printed threads. Didn't think it existed for real until I've seen one on the Quekett website:
.

Hope you succeed; IMHO, for accurate axial threads, the tapping piece as well as die must be fitted on a precision machine - namely, a lathe...

RMS is equal to W0,8×1/36. On the net I found some makers of those tools. They are all German and ask very high prices of about 400 - 500 USD für a tap or a die. Did not find any low cost source but there will be some Chinese made stuff for sure.

The taps exist:
https://www.thorlabs.com/newgrouppage9. ... 9&pn=46720
Its called TAPRMS
I think that everone dreams of one

But maybe push-fitting an RMS extender into a printed hole might be another workaround?

Ah great thanks! They have also the C mount! But no die yet. ?
100$ apiece... I'll think about it... while dreaming for a lathe...
Meanwhile, yes, the 3D printed (crap) threads are getting "opened" with a scrap objective

Both tap and die are listed by Baer : https://baer.tools/en/taps-dies/thread- ... ound-dies/

But, for the price of the pair, you could buy a useable lathe.

MichaelG.

I found an RMS tap a few years ago for (recollection) around $80. Believe it was on Ebay, sourced out of China. The quality was OK.

So affordable ones are (were?) out there. You might try some of the safer Chinese e-commerce sites?

If you need to cut male threads, a screw-cutting lathe is pretty much the answer. That or the suggested work-around of finding something with the thread (parfocal extender etc.) and marrying it (light push fit, epoxy) to wherever it's needed.

The taps are much less expensive than the dies. Dies tend to run around 300.00 with only a few suppliers showing up in a search, Baer and someone in the U.S. who I can't remember that actually makes them, and maybe the U.K. Then shipping enters in. Very costly unless you are using it a lot.

I have had to repair a few male threads and sometimes, a harder than the male thread, female thread, will do as a chaser but I have also cut some new threads on brass with a metric that is close to an R.M.S. thead. If the turns are few , it works. An option is to get a metric tap too and chase the female with it, to give a better match.

As of March 2020, there was a 20X .75 metric die on ebay. I paid 9.00. Thread below.

viewtopic.php?t=7609

patta wrote: ↑

Tue Feb 15, 2022 1:23 pm

Meanwhile, yes, the 3D printed (crap) threads are getting "opened" with a scrap objective

Honestly I have not had this issue with 3d printed threads, thoigh you have to account for inner diameters peinting a little bit tighter than specced (usually around 0.3mm in normal thread ranges on my machine).

Aha; sorry for duplicating threads then! The plan is
1- get a lathe
2 - park it in the living room
3 - use it for contract works, sparing enough money in order to
4 - buy the 400 Euro die from Baer tools!

I think I'll keep all those as dream... meanwhile, more adjustments with 3D printed threads! Maybe the 20 0.75 if comes nearby!

I've printed down to 0.5mm pitch and up to 65mm diameter threads, male and female, and the results have been quite good once I got the dimensions dialled in. Obviously it's not as good as metal but it has worked exceedingly well for me.

what are you trying to do? adapter?

patta wrote: ↑

Wed Feb 16, 2022 5:51 pm

Aha; sorry for duplicating threads then! The plan is
1- get a lathe
2 - park it in the living room
3 - use it for contract works, sparing enough money in order to
4 - buy the 400 Euro die from Baer tools!

I think I'll keep all those as dream... meanwhile, more adjustments with 3D printed threads! Maybe the 20 0.75 if comes nearby!

Not really a duplication but it does point to a glaring deficiency regarding this forum. No stickies. Not necessarily is the R.M.S. thread thread a sticky but there are quite a few threads that could or should be. Not necessarily a profit maker I guess.

Not answer to the question persé, just offering an alternative.

if your goal is simply to use the tap/die to clean up plastic 3d printed parts, you could go about it another way:
the usual places for cheap chinese stuff sell a lot of these adaptors, from RMS thread, to whatever other thread or tube sections made from plastic or metal.
You could simply acquire some of those and design your 3d printed attachments to glue with epoxy to them. That would give you custom part with high quality plastic (or metal) threading. I think it will be easier to glue a flat adaptor surface to a matched 'buildplate surface' of a 3d printed part than to accurately thread a 3d printed part with a tap or die.

btw, for opening threads with a existing opposing thread, like 'scrap piece', it helps a lot to cut (grinder or dremel will give best.sharpest surface) a slit across the scrap piece threads so there is a sharp edge along the direction of rotation (you can also file or grind the trailing edge a bit to allow removed material to go somewhere). it works well for soft materials.

Can you point to a Chinese source for a cheap R.M.S. tap or die? I would love to have both.

eBay currently lists '0.8" - 36 TPI Straight Plug Tap, RMS thread / microscope - Unbranded, Sharp' for US$60
https://www.ebay.com/itm/304542577734