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MountainMan
08-10-2018, 06:32 AM
I recently got a Unimat Sl-1000 and the t nut to hold down the tool holder fell apart in 5 pieces on me. Does anyone know where I can buy these at? All I need is one to make a few off of.

wmgeorge
08-10-2018, 08:40 AM
Is it just a standard thread Metric? Or https://unimat.homestead.com/

CCWKen
08-10-2018, 11:30 AM
...the t nut to hold down the tool holder fell apart in 5 pieces on me.
Five pieces? What's it made of, dried out plastic? Making T-nuts should be part of everyone's practical experience. It's not rocket surgery. :cool:

BCRider
08-10-2018, 01:03 PM
..All I need is one to make a few off of.

This last sentence tells me you've got a mill that you can use to make your own. If you've even got most of the pieces of the old one you shouldn't have any trouble designing a new one. Even if you didn't have the pieces you should be able to measure the T slot dimensions and design your own.

Even if you don't have a mill and would be making a "top hat" shape then filing the sides down to make it fit the slot you should be able to fake it for now with something like a cut down nut or small scrap of steel that you thread to take the bolt. Then you can use the lathe to make the top hat which you then file to fit the slot.

Paul Alciatore
08-10-2018, 01:21 PM
The original Unimat Tee nuts are a poor design. It appears that they were turned on a lathe, not milled. I think the chief purpose of it was to make manufacture cheap and fast - in the 1950s. They were probably made on an automatic screw cutting machine (lathe). All my original ones are either broken or severely distorted. Here is the drawing that I have been working from to make new ones. I make then in strips and cut off the lengths that I need as I need them.

http://bbs.homeshopmachinist.net/attachment.php?attachmentid=3424&d=1533921242

The dimensions do not completely match the original Unimat ones, but they have proven a lot more durable in use. I haven't had to retire a single one of the replacement nuts that I made. Part of the reason for this is this design has a lot more steel in places where it beefs up the nut. The dimensions in my drawing are to allow the use of a 3/16" x 1/2" strip. Only the 1/2" width needs to be reduced: you use the full 3/16" height. Almost any steel alloy will suffice.

And YES, it is a standard metric thread: M6. Almost all the threads on the Unimat are M6. The headstock spindle is a non-standard metric thread: M12-1. There is a chart of Unimat thread sizes here:

https://unimat.homestead.com/

flylo
08-10-2018, 01:30 PM
Is it just a standard thread Metric? Or https://unimat.homestead.com/

Great site, Thanks for posting it

BCRider
08-10-2018, 01:43 PM
AAAAND..... PAUL SLAM DUNKS THE BALL! ! ! ! The crowd goes wild ! ! ! ! :D

CCWKen
08-10-2018, 02:08 PM
Dang! Those are small. :eek:

J Tiers
08-10-2018, 02:12 PM
And, on some that I have seen, parts such as that are made of something very much like zamak, which would certainly explain the "broke in 5 pieces" deal.

BCRider
08-10-2018, 03:41 PM
Dang! Those are small. :eek:

So is the lathe! We're talking about something that overall fits easily into the footprint of a desktop 'puter's keyboard after all.

greenie
08-11-2018, 07:30 AM
To make as many as you require, just get a bit of keysteel that fits into the B-I-G-G-E-R slot in the table, turn a shoulder that will fit the smaller slot and WILL NOT sit up proud of the table surface. Drill and tap it to whatever your heart desires, normally 6mm will suffice, cut it off anyway you can, be it with a parting tool or heaven forbid, using a hacksaw. OK, keysteel is crap steel, but so is the original T nuts also made from licorice.

Mcgyver
08-11-2018, 07:47 AM
All the Unimat T slot nuts I've, and I've bought and sold quite a few over the years, have been steel and well made like the rest of the Unimat kit.

As for making them, all you guys suggesting so, have you used a unimat? Yes it can be done, but it would tedious enough that asking where to buy is more than a fair question.

try here, this guy buy and sells unimats so worth sending an email

http://www.tomstoolstore.com/

Paul Alciatore
08-11-2018, 03:59 PM
Dang! Those are small. :eek:

Well, M6 is smaller then 1/4-20. Not much, but a little. The Unimat is made to metric dimensions, but it is basically a 2 X 6 in English units.

All the OEM Unimat Tee nuts I have seen were steel. Soft steel, but steel. The real problem was that they minimized the design to the point where their strength was marginal, at best. The simple corrective action of just designing them more like standard Tee nuts seems to be enough to fix that. I made my replacements well over a decade ago: the drawing that I posted was dated 2002 in my files and it is a BMT, not the original CAD file. So I have been using that design for over 16 years and have had no problems or failures.

J Tiers
08-11-2018, 04:32 PM
Will take your word on the material..... steel is not known for "breaking in 5 pieces" though.

Paul Alciatore
08-11-2018, 05:29 PM
Well, I said all the ones that I have seen. I have the DB200, not the SL. Bought it in the 60s. The SLs are aluminum castings. I wouldn't be surprised if they went to using plastic for some parts.




Will take your word on the material..... steel is not known for "breaking in 5 pieces" though.

Gary Paine
08-11-2018, 05:41 PM
I roll my own T-nuts. Even before the mill, I machined them on a lathe milling attachment. I do agree, though, it will take a while to remove the material with the little bites the Unimat will take, and I think the T-nuts would be required to hold down the workpiece.
I am chiming in here to remind not to make a circular nut that fits the groove and use that as an easy way out. There is not enough bite and it is risking the topslide slot. Same warning not to use too long a bolt/screw into the nut, as it should be just long enough not to come in contact with the bottom of the slot or it too can blow out the topslide. That's why I overdo it and make my own the whole width of the topslide to minimize stress in any area. After all, you can't buy replacement parts at the local hardware store.

J Tiers
08-11-2018, 10:37 PM
Well, I said all the ones that I have seen. I have the DB200, not the SL. Bought it in the 60s. The SLs are aluminum castings. I wouldn't be surprised if they went to using plastic for some parts.

Aluminum castings could explain the observed breakage.

I have a t-nut on one toolpost that I machined out of aluminum extrusion many years ago. That has held up very well, and has a 3/8-16 screw going into it, so there is some force on it (not on a Unimat)

Paul Alciatore
08-11-2018, 10:40 PM
When, on that day long ago, I found that I needed new Tee nuts I had several that were distorted but still usable. So I was still able to use my Unimat. The Tee nut that holds the tool post down is the same size as the ones used for every other accessory. You get two with the milling vise, two with the milling table, etc.

But it is a very small and simple shape. It wouldn't take very long to file down a strip of the 1/2" x 3/16" steel stock that I used. Saw cut, file, drill, tap, DONE. I am making some steel handles for some storage slides in a new work bench and I had to file off more on one of them to make the end round than on one Unimat Tee nut.

As for doing them in the Unimat, I think a couple could be made in an hour or so. I have a milling set-up for my SB-9 but it also is limited to small bites.