Build and Intro

**swisscheese** · 28-09-2013

Thanks for the fast reply jonothon, good man. On the train at the moment so wont do full reply. Are the photos showing up out of interest. Almost certainly wont be using machine for metals 99.5 percent o the time.

**swisscheese** · 21-10-2013

Update

So the build has been coming along slow as uni is getting in the way.

I used the west system resin recommended and it worked really well. However it could have been a lot better if i had of sealed the edges better as quite a bit dripped out so there were some low spots.

The x axis is nearly complete, I'm just waiting on the belt and pulleys to arrive. I ordered 20 tooth pulleys and a 2525mm long 5mm pitch 15mm wide htd timing belt. Belts will also be used for the other two axis.

I had to use steel for the gantry as no one would supply the aluminium I needed. I could only get aluminium if I brought a 6m length.

I'm having a bit of trouble with working out how to arrange the bearings for the z and y axis. I know I asked in my first post about mounting the supported rail so it moves with the spindle but I want to know how important this is?
I ask because it will save a lot of mucking around if I can mount it the other way with the bearing blocks on the spindle.

Thanks again

**EddyCurrent** · 21-10-2013

I could only get aluminium if I brought a 6m length.

Maybe you could have sold the remainder on ebay for profit ?
I think another reason for putting the Z rails on the moving plate is to add stiffness to the plate, you could argue that the rails should not be used to add strength but undoubtedly they will. There are plenty of machines with the rails mounted both ways and likely it will work both ways, it's just that one way is slightly better than the other.
Machine is looking good by the way, I can see the frame is well put together but I don't see any triangulation such as diagonals. Will you be fitting adjustable feet ? or maybe your floor is flatter than mine. As Jonathan says the 2.2kw ER20 spindle would have been so much better and I suggest you should go this route to have the 1/2" capability.
I found the round rails to be a bit bulky for the Z axis but they do allow more space for the ball screw.

**swisscheese** · 21-10-2013

Hi,
I could have done that but a bit meh with the fuss involved.

I think I will mount it with bearings moving with spindle. It just makes everything a lot easier. I'll take into account the lost rigidity of spindle mount without the rails. 20mm thick aluminium seems to be the standard isn't it? I think it should suffice. And yes having some hywin type rails would be nice but the ballscrew is the limiting factor at the moment as I can't machine into the aluminium so their profile could be lowered. Hmm maybe a project after this is complete is to make a new z axis with hywin rail.

The table is bolted to the ground in 8 spot(one each leg) so I'm guessing this might mean I don't need triangulation?? Will wait and see. The epoxy leveling was done after. This means that I can never move the machine(as it would have twisted when I bolted it down), at least without redoing the epoxy each time.

**EddyCurrent** · 21-10-2013

I'm going with 20mm aluminium plate. It sound like a good idea to fasten the machine down but I think you could still have adjustable feet too just in case

I'm not an expert on cnc (yet

) but from your pictures, my past engineering life and what I've learned from this forum, I'm thinking the square tube bracket down to the x axis ball screw is not strong enough. It would be better if there was a triangular fillet each side to prevent flexing, I can imagine it vibrating causing tiny oscillations.

**JAZZCNC** · 21-10-2013

Originally Posted by swisscheese

The table is bolted to the ground in 8 spot(one each leg) so I'm guessing this might mean I don't need triangulation?? Will wait and see. The epoxy leveling was done after. This means that I can never move the machine(as it would have twisted when I bolted it down), at least without redoing the epoxy each time.

If you had triangulated and made a stiff frame then yes you could have moved the machine. Even now you can move the machine but you will need to ensure the frame is not in twist when set in new location. The rails will still be on the same plane if no twist exists has they levelled on same plane and the only thing you can introduce is twist.

Regards the rails on front then mostly depends on how much extension you have on the front plate when cutting and also what your cutting. If mostly extended and cutting harder materials, hard woods,aluminium etc then it will make enough of difference to matter. Low extension and softer materials it will hardly make difference.

**swisscheese** · 23-10-2013

Thanks for the replies

Few Questions

How tight should the belt be? As in should I be able to turn the pulley on one side a little bit(maybe 8th of a turn) while holding the pulley on the other side still? It runs between the two sides and has a center distance of about 1100mm.

Also with the pulleys the length of the bore is about 29mm and it has two set screws. The shaft for the pulley on the end of the ball screw is only 15mm long. Should I be concerned that the shaft isn't long enough? Is tightening down the set screws onto the round shaft fine or should I grind down two flat areas on the shaft for the set screw to tighten onto?

thanksssss