[Robert_83]

Hi everyone. I´m new here. Long time reading and learning. My name is Robert. I´m 41 years old and I lake to make things.

I´m going to build a small glassblowing lathe using a 30150 aluminium rail and 2 MGB15C with 2 carriages each rail. The linear guides will be in the first and fourth rail, so 90mm separate.

I´m new on this, so I´m not sure what I have to put over the carriages. I look for "gantry plates" but none of them has the appropiate holes. It should have holes spaced 20 and 25mm for the holes of each carriage, but also to allow the separation of the guides and the carriages



I could make one in my mini mill. But its mini, and not sure 100% of its acuracy, so I preffer to buy a a plate with the holes already drilled in the exact location

Any idea? Thank you

best regards

[joeavaerage]

Hi,
I use larger rails/cars, 20mm. The distance between centers of the cars is 200mm x 200mm in both directions

Clearly the further apart the cars the better, it results in a more stable plate......but it also means less travel for a given length rail.

For example say you have a rail 600mm long, and you decide for best stability that the cars be 200mm apart (centers) and each car is 40mm long.....then: Travel =600 -200 -40 =360mm.
So despite having 600mm long rails the travel is reduced to 360mm, and you probably want a little clearance each end, so 350mm effective. You might increase the travel by reducing the gap between the
cars but have a less stable result. Its a balance.

I put a 275mm x 275mm 20mm thick steel plate on top of the cars. I had the plates (I made three, one for each axis) surface ground. Cost me $90NZD and a plate of scones to get them ground....and thereafter
they are flat and parallel to better than 0.01mm.....easy! I drilled them my self. I deliberately chose a regular square drilling pattern and all three plates identical, so when I made one jig I could do all three and be 100% assured they are
all drilled the same.

If I were you, I'd get some steel plate, maybe 20mm or 16mm but down to 12mm would be acceptable laser or plasma cut, then surface ground. Easy and cheap. I'd also suggest that you make the center to centre
distance of your cars the same in X as in Y, ie ??=75mm as you have drawn it above. If you do not feel that you can drill them accurately have someone put the plates in a CNC mill and drill pilot or starter holes.....
sure it will cost, but even a modest CNC mill will be better than 0.02mm accuracy.

Craig