Bridgeport Manual to CNC conversion...

[Davek0974]

Based on advice, 750w AC servos and 2:1 is ideal on a bridgeport so that is whats going in, totally overkill for the Z axis but the price of smaller motors is higher so i cant see the point really, keep it all the same.

Got a few parts on the way - stainless panel mount keyboard, stainless panel mount trackball, some bits from the box at work - nice 10-turn pots and dials for FRO & SPO controls, a few spare relays and other bits and bobs.

Just about got a source lined up for a ballscrew kit - this bit really hurts the wallet :(

Does anyone have a drawing or sketch that would give me the dimensions of the right table (X) bearing bracket and the front (Y) bearing plate??

Mine will be missing as I have the original 6F power-feeds which will be taken off when i convert.

I can get the parts but the prices seem silly and they surely must be an easy enough part to make up from steel or aluminium?

Thanks

[Davek0974]

Drive belts - HTD5mm x 15mm wide big enough?

[JAZZCNC]

Drive belts - HTD5mm x 15mm wide big enough?

They'll work ok but i'd be more inclined to go with 25mm for Mill with heavy bed.

[Davek0974]

They'll work ok but i'd be more inclined to go with 25mm for Mill with heavy bed.

Hmm, will have to check pulley dimensions will fit machining on shafts, there is a conversion kit which uses 1/2" belts, I thought that was a little weak so went for the 15mm size as i used before.

Will look into the 25mm size

[Davek0974]

Drive belts, just had a chat with a very knowledgeable guy and it seems HTD is the best option here, GT is better but more expensive all round. The backlash concern is valid but equates to approx 0.25mm linear which if i have my sums right on 5mm pitch screws and a 75mm pulley will give me an error of 0.0053mm - I think thats acceptable on a 30+ year old machine ;)


He did however strongly recommend going for 8mm pitch and 20-30mm wide belts.

Can't use 8mm pitch as you can't get the needed ratio in as the pulleys are so much bigger so will have to be 5mm pitch.

[Davek0974]

CSMIO unit on order, motors on order, ball-screws ordered, wallet crying :(

Panel controls...

With the Bridgeport you have to run in reverse when in low range, is there a way to have this done in Mach3 or will it still be a Hi/Low selector switch on the panel?

The VFD for main spindle, with the vari-speed mechanical system I'm not sure if i should try using the vfd as variable or leave it fixed at 50Hz, the top speed is limited to 3500rpm absolute max as it tends to wreck the spindle bearings above that and low down it probably would not have the torque needed, so stick with mechanical ?

Main spindle on/off manual control - would these buttons control Mach3 or would they control the vfd directly?

Just looking for ideas here.

[Davek0974]

Food for thought...

While waiting for the screws & motors to arrive, should I strip her down to the bones and clean / paint the old girl ;)

Would take a bit of effort as it would need space clearing to get the engine hoist in to lift the head, ram, collar, bed and knee off.

Could be useful as it would allow me to check for worn out bits, split lube pipes etc.. Would also make the build and wiring a cleaner job by getting rid of the grime and muck.

Hmm....