How to Attach linear slide to 8020

[klick0]

Hey, i've been working on my new CNC machine, and am wondering what others have done to mount linear slides to 8020. Now obviously the answer is to get a T-Nut and drive a screw into each hole of the linear slide, but are there T-Nut's available of the appropriate size?

I have many t-nuts for my 8020, but of course the bolt is way to big. I've purchased (not yet received) stock T-Nut material with no holes in them, i'm planning on drilling/taping bolts into these that match the size of my linear slides (which are HiWin 15mm, also i'm using 15 series 8020). So I was going to line these up with custom threaded T-Nuts and that would be that.

Is that the right approach? I was just wondering if I missed some much simplier approach, or T-Nuts that are for this already made. Making 100 T-Nuts and threading them all doesn't sound like much fun, but it's required to make the machine solid.

Thanks,
Ross

[High Seas]

Ross,
Don't know about HiWin track - but I took some steel bar stock, aligned it, clamped it, then carefully drilled and tapped through each hole using allen cap machine screws that fit my track.
A lot of effort as you say, but it is one length of T-Nut like bar. The bolts were loosely fitted, and the track slid into the 8020. It was useful to tighten only some until I got the system square.
Your approach with many T-Nuts should offer the same set up - but a lot of work as you acknowledge. And it should work - IMHO.
Sorry no pics to offer and the ones in my gallery don't show it very well either.
Hope that helps.
Jim

hmmm maybe that is something ahern could offer from his cnc store????

[LeeWay]

Why not just bore out the ones you have and retap those? Holes are already centered and will act as a pilot hole for a bigger bit.
I actually used 5/16" carriage bolts when I installed the rails on my Y axis for my mill. The spacing wasn't exactly what I needed, so I had to also use 1" flat bar. I tapped the bar to fit the rails then. My rails were the wide type with two rows of holes. I needed the room there for the ball nut anyway, so the extra 1" height on the rails was perfect.
You are on the right track with using the T-nuts. You need to be able to use the cap screws that the rails are designed for. This will give the best rigidity.

I did use some steel flat bar to mount the bottom of my column. Drilled and tapped like I needed. It was nice to slide the whole thing into the slots, but singles can be fed in there as well with some patience.

[schbrownie]

Depends on what type of rail your're mounting. If you're mounting a large enough rail, you can just bolt it directly to the 80/20. If you're going smaller, I would get a piece of flat stock aluminum and bolt that to the rail then bolt the profile rail down to the piece of flat stock.

You can also consider using redi-rail from Pacific Bearing. (www.pacific-bearing.com). I use this product on most of my machines because it's usually less expensive than a profile rail (unless I find a good deal on eBay) and it's a nice wide profile that can bolt directly down to an 80/20 extrusion.

By the way... I prefer to use T-Slots (www.futuraind.com) becuase they have a flat face as opposed to the ribs on 80/20's exterior plus they are about 20% less expensive. The ribs on 80/20 are much harder to keep clean and you have to power wash/scrub with a toothbrush to get all of the dirt out of each of those little ribs. Bosch Rexroth also has a nice line of flat exterior slotted extrusions.

Hope this helps,

~Jon

[ahren]

On my machine, I just got a piece of cold rolled steel bar that would fit in the T-slot (for 15 series 8020, this is 5/8" x 1/8") and drilled and tapped holes. It's nice to have a continuous piece rather than individual T-nuts for ease of alignment and assembly.

I did the drilling and tapping on a mill, but the idea of clamping the steel to the bottom of the rail is a good one. I would then get either a tranfer punch or a drill bit that's exactly the size of the through hole in the rail, and use the rail hole as a drill bushing (hey, it's hardened!) to start my holes. Obviously, you need to switch to a smaller tap drill once you get the hole started, but this will keep your bit from wandering.

Ahren
www.cncrouterparts.com

[guru_florida]

I have my 20mm (or 25 I cant remember!) rail secured directly to the 8020 with T-nuts and it works good. If you have the machine/tools attach your 8020 to your base plates, then mill the top of each 8020 extrusion by a hair. This will ensure that both rails are precisely the same height before you mount the rails. I don't have the tools to do this myself, but its recommended. Even without my rails seems lined up fine in operation.

[klick0]

I got some 12" pieces of T-Nut "stock", which i've been drilling and taping with the proper dimensions. I think it should work properly, I couldn't find lock washers for the #8 size machine screws so I was going to use loctite. Is that sufficient or should I find some lock washers (order online easily). Not sure if they'll fit in the hole though, it's pretty tight as it is.

[LeeWay]

I just used a little locktite. Be sure not to use the red or permanent. Blue, purple or green should do the trick. Green is for seeping into the threads though and may not work right through a rail and then into the tnuts.

[lovebugjunkie]

Locktite…great stuff I’ve had it hold when nothing else would stay put.

If you go with LeeWays suggestion but sure to take his advise on the red. I used it to mount some after market seat rails to an old 911 Targa project car. Had to remove them a few weeks later for some work I was doing. Only way I was able to get the bolts out was to drill them and re-tap for new bolts. Made for an enjoyable afternoon.

[ahren]

FYI, the extrusion flanges are out of flat by 2 degrees (at least in 8020), and flex to flat when you tighten a t-nut against them -- this is by design, and creates a locking feature inherent to the extrusion. So you may not even need loctite, although go ahead if it makes you feel better about it. It can't hurt.

Ahren
www.cncrouterparts.com