[Beowulfenator]

Hello!

I am relatively new to the t-slot profiles, so once I got a scrap piece in my hands I saw something unexpected:


The parts marked with arrows are somewhat recessed, probably to make the t-nut joint stronger. But what happens if you mount something narrow, like a rail for a linear guideway? Wouldn't it be recessed relative to the profile area? Maybe I need a shim that is as wide as the profile (40mm in my case)?

Can someone enlighten me please? Thanks!

[PaulRowntree]

The recessed slot sides are pulled up flush when you tighten the bolts using standard wide components, so yes, a narrow component may be slightly down unless you use a wider support piece between the rail and the extrusion. I believe the recessed walls make for an internal 'belleville washer' effect, providing some tension on the bolt shaft.
Any intermediate piece should be sufficiently stiff that the T-slot walls bend, not the added piece. Thin, weak intermediates would give very poor support for your rails, since the rigid rail would be trying to attach to a distorted (curved) shim piece.
Cheers!

[Beowulfenator]

Thanks, Paul!

So let's say the weight is not a concern, as the rails are mounted on a stationary gantry. Would it be a good idea to use a 40mm wide strip of steel as a shim? Do you think making this steel piece 3mm thick would be enough?
Also, if the weight is a concern, how thick a strip of aluminum should be?

[neilw20]

3mm steel or 5mm-6mm aluminum I think would be OK.
Or you could just us big flat panel washers. depends how stiff your machine needs to be.
You cutter loads, determine how stiff it has to be.
Once the machine flexes more than the chip thickness, all bets are off, and you have something to chat(ter) about.

[Fabricator08]

I mounted mine by drilling the the slot to the back. used a screw with an angle under the head surface. slid the screws in the slot and slid a allan wrench in from behind through the hole and tighted. The rail centered up perfectAttachment 263570

Hope the pictures worked.

[noplace]

Hi, Im about to design a machine with this setup, my rails will be wider however ( 35mm ) on 40mm t-slot profile, do you think this problem will affect me? can i do with the washer way?

Thanks!

[mactec54]

Hi, Im about to design a machine with this setup, my rails will be wider however ( 35mm ) on 40mm t-slot profile, do you think this problem will affect me? can i do with the washer way?

Thanks!

A washer I hope was just a joke I think,But you never know what some of the posters are thinking, Linear Rails need to be mounted on a machined surface, it will depend on how much clearance the bearings have, as to how flat the mounting surface has to be, if it is not flat enough for the bearing clearance then there will be binding & jamming of the bearings

Some suppliers that sell the aluminum extrusion, do offer it with a machined surface, the best way to mount them is on a machined plate with a shoulder, to suit the rail, so the rail can be fitted up against the shoulder, this helps to keep the rail straight

The rails are not straight, so need a straight/flat surface to be mounted on

[mactec54]

noplace

Here is one that offers a mill surface, for linear rail mounting,( Misumi ) this is still not ideal for linear rail mounting, but for hobby builds, this will help to you build a better machine