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Whats the correct size clamp kit for the mini mill?

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Philip A26/11/2020 13:29:42
33 forum posts

Finally purchased an X2 Mini Mill (Sieg).

But I can't find the right size clamp kit. The slots on the mill are apparently 12mm, but I'm not certain what the stud size is. The Arc Euro kit uses 12mm nuts and 6mm studs, but Mini Machine Shop is saying that 12mm nuts with 5/8" studs fit.

JasonB26/11/2020 13:48:16
19568 forum posts
2142 photos
1 articles

Something wrong with teh LMS size as 5/8" is bigger than 12mm slot.

ARC list it as 8mm slot not 12mm and M6 sounds right for an 8mm slot.

Philip A26/11/2020 13:52:44
33 forum posts

Mini Machine Shop link:

Sorry 3/8" studs not 5/8".

JasonB26/11/2020 13:57:19
19568 forum posts
2142 photos
1 articles

Who did you but the mill from and is it an X2, SX2 or an SX2P as they have different tables depending on who you buy from

Edited By JasonB on 26/11/2020 13:59:51

Philip A26/11/2020 13:59:21
33 forum posts

Sieg SX2P from Arc. I just found the Arc specs, they were in a separate tab on the product page, and you're right the slots are in fact 8mm.

I've only found 24pc clamp kits in the 8mm slot, 6mm stud size. Other sizes come as 54pc. Is 24pc ok?

Nicholas Wheeler 126/11/2020 14:00:39
447 forum posts
25 photos

I bought mine from Cronos about 15 years ago.

It uses T-nuts that fit the slots well at 11 and 17.5mm wide, with M10 hardware.

The hardware and clamps are much bigger than most jobs need, and get in the way.

Every time I use them, I tell myself it's past time that I made some new nuts and clamps using M6 threads, like in Harold Hall's articles/book.

I notice that Arceuro do smaller step blocks that would be more suitable for this size clamps.

Thor26/11/2020 14:01:24
1324 forum posts
40 photos

Hi Philip,

I use M10 studs in 12mm T-nuts on my X2 Mini-Mill, my home made ones use M8 studs and 12mm T-nuts, M8 gives more than enough clamping force for the work I do on my MiniMill. I have also made M6 clamping studs that I use for light work.


old mart26/11/2020 14:02:46
2472 forum posts
169 photos

I would measure the width of the slots and get the next size down metric set. Standard sizes would be 12,10 and 8 mm. Go for metric as it is easier to add to using easily available studding, nuts and washers. The most useful sets are about 50 piece with a nice stand.

Nicholas Farr26/11/2020 15:30:04
2551 forum posts
1211 photos

Hi, most of the mini clamp sets are 24 piece, but Chronos do a 36 piece one.

Regards Nick.

JasonB26/11/2020 15:39:25
19568 forum posts
2142 photos
1 articles
Posted by Philip A on 26/11/2020 13:59:21:

I've only found 24pc clamp kits in the 8mm slot, 6mm stud size. Other sizes come as 54pc. Is 24pc ok?

The 24pc will be fine and I'd probably opt for that over the chronos one as the clamps are two different lengths. You can soon make a few more nuts and cut up a length of studding if you find you need more capacity

Henry Artist26/11/2020 15:59:07
120 forum posts
46 photos

I would strongly urge you to telephone Arc and discuss your requirements with them. They are super helpful and know what they are talking about. They also do starter sets with a selection of things in them that you will find useful and can advise you on which one will suit your needs.

Having a clamping system based around M6 fasteners means it is real easy and inexpensive to get extra studding, allen screws, hex nuts, and washers. You can never have enough T-nuts but since you have a shiny new milling machine guess what your first milling project might be... wink 2

Clive Foster26/11/2020 21:39:58
2533 forum posts
82 photos


Its an inescapable fact of life that the common step block and bar clamping kits are mostly too large and and cumbersome to be ideal. Whatever the machine.

A standard kit will get you started but stocking up on materials to quickly DIY something for "this" job is well worth while.

For 6 mm threaded T nuts steel strip 12 mm by 3 or 4 mm thick will be fine for L or U shaped clamps made to size. Simply drill, bend and file a bit off if too long or need to get round an obstruction. 12 mm by 6 mm alloy will be fine for clamp bars cut to length and drilled appropriately. Either run right across the job or support the free end on a suitable piece of scrap material. Heck you could even go fancy and tap a hole in one end for a jack bolt. I did back in the day in 3/8" x 1/2" steel for my baby BCA. Looked good but whether the effort was worthwhile is debatable.

Quick, dirty and here right now is the attitude.

You will need some extra T nuts, 6 mm studding, joining nuts and penny washers to hold the DIY clamps down. Not a fan of pulling up directly on Tee slots. Clamping the Tee nut in place with a joining nut on top of a penny washer and screwing the stud into the joining nut is better engineering.

Great thing about having the makings to hand for fast DIY is that it doesn't matter what happens to the clamp. If its easier to cut through it than move it then who cares if the cut scraps it. There will be another one along in 5 minutes! Scrapping a clamp beats the heck out of spending an hour re-aligning things when the job shifts whilst you are moving clamps around. Or worse scrapping the job 'cos you didn't notice it shifting over by 3 gnats todgers.

Simple DIY clamps won't be as strong as the commercial kits but its a rare ME job that is strong enough to take the extra loading that a commercial bar can apply without distorting under the clamp and an even rarer one that can be done with a big enough cut to need that much grip.


Nigel Graham 226/11/2020 22:00:57
913 forum posts
16 photos

The one point to note if you make the T-nuts is to ensure the screw won't pass right through the nut. If it does it will bear on the floor of the T-slot, putting an unfair strain of the slot flanges, and can even break them.

The commercially-made ones have the threads staked to prevent it happening.

Clive's advice to use a joining-nut improves on that by places the flanges under compression, with equal pressure from above and below, and on both flanges.

A dodge I also use, where the stock or work-piece itself allows suitable holes to do this, is to screw the metal itself down to the T-nuts (with interposed packing!).

Worth if making T-nuts, making several sets of the same profile but with differing hole sizes - say, M6, M8 & M10 or their inch equivalents, so you can match the clamps or direct screws to the work better.

The about-M10 commercial sets seem to be 3/8-in BSW. If so, as BSW fastenings are becoming rarer, save as many as you can find to extend the clamp set. I've not ascertained this but they might in fact be 3/8 UNC - both are 16 tpi, with different profiles.

Clive Foster26/11/2020 23:10:19
2533 forum posts
82 photos

If you make your own T-nuts the easy way to ensure you cannot screw the stud right through is to use a second cut tap and stop tapping just as the end thread breaks through. Generally that will leave a little over one pitch that a stud or bolt won't screw through.

But it does depend on your tap.

Theoretically best way is to put a stop on your plug tap so it leaves one clear thread untouched when following the second cut tap. But that's more hassle.

Another effective way is to tap right through and punch the end thread down with a ball bearing or hemispherical ended punch sitting on the end thread. Thats the way I do them but I use a tapping head in the pillar drill so I go right through. Need to be creative to stop the ball flying into hiding. Sitting it into a drilled hole about 2/3 rds diameter deep in the end of a short round bar and peening the edge round to hold it works for a few but it will eventually escape.

As ever lots of methods. What works for you with your equipment is all that matters.

I prefer light alloy for shop made nuts. It's more than strong enough and if a chip gets hung up it bites into the alloy rather than your table. If there is any inaccuracy the T nut will bend rather than the table. Scrapping a T nut, especially a home made one, is a mite cheaper than sorting a damaged mill table. Ultimately T nuts are consumables.


Edited By Clive Foster on 26/11/2020 23:15:31

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