CNC Arboga U2508 Mill Conversion

[Ross77]

So is the standard set up an AC bearing at the bottom and then 2 deep groove at the top? sounds a bit strange. for 2 bearings at the top I would expect a roller bearing at the bottom (radial loads) and then 2 opposing AC bearings at the top (axial loads).

I know what you mean about getting it working to then build the upgrade parts. Sounds like we are doing very similar projects. I think I will watch your progress and learn from your mistakes.

[Swarfing]

No it is a taper bearing at the bottom

[Ross77]

No it is a taper bearing at the bottom

Ok that makes sense, deep groove bearings pre-loading a taper which can take axial and radial load. I would have thought an AC at the top would have been better as you still get the speed increase from using ball bearings but not the heat issues with pre-loading deep groove bearings, (as you are forcing them to run on the edge of the race) excessive heat will cause expansion and reduce the pre-load on the bearings and therefore rigidity.

This is the theory so it will be interesting to see if in a hobby environment it is actually a problem. that is what I'm trying to find is the balance between the ideal design and what works in practice.

[Swarfing]

Monday i had a chance to cast some Ali blanks for the pulleys. Got one machined up yesterday evening and the other tonight. The one on the left i will have to make again. Stupid me let go of the cross slide whilst plunging the pipe threading tool in for the ribs and it pulled itself in (tool slightly too low). This in turn locked and flung the pulley out of the chuck damaging it. I will use it for now so i can mock things up.



Made these to fit 'J' section 5 rib belts, size 559mm long or 22" in old money. Belt will be here next week.

[Ross77]

looks good, shame about the slip, why is it always the last operation that goes wrong?

when will it be working then?

[Swarfing]

Good question? Time is very finite that i can use so it really is a question of slowly but surely at the moment. Need to do some casting which i will do over the weekend hopefully. I can then build the motor supports and remake the left pulley. Now i have these bits i can start laying the motor out and fix the top plate, work out how i'm going to fix the spindle in place as well as make a bush to lower it in the head slightly.

Will grab some more pics of all the other bits as soon as.

[tojan19]

Did you ever finish the conversion? Thinking about doing the same on my old EM825.