i have a generic Chinese 2.2kw (~3hp 6-24k rpm) water cooled spindle on my current cnc table that we use for aluminum sign making, and have been throwing around the idea of making a low speed spindle adaptor that is driven by the 2.2, and uses vbelt/timing belt for the rpm reduction. the low speed spindle would be built myself, using a grizzly R8 spindle and bearing assembly, and set up to use the tormach TTS tool holders, and later on a pneumatic cylinder to allow for a tool changer.
the setup would be something like this...
Attachment 208548
under normal use, the 2.2kw spindle would be in the holder by itself.
when the low speed spindle is needed, the main spindle would be slid out and inverted, and reinserted in the outboard position.
the low speed spindle would then be slid into the inboard position, a half inch shaft with a set of v grove or timing style pulleys would be inserted into the collet holder, and the chuck tightened.
before i get started on this, a friend recommended that i register here, and run the idea by people who have alot more experiance with this type of machine than i do.
now that i have explained the setup, these are the questions i have.
1. is there a cost efficent (under $500 usd) low speed spindle alternative?
2. v belt or timing pulley?
v belts would allow some slippage if the tool bound up, but i can easily make any size pulleys i want for the reduction ratio
timing pulleys would eliminate slippage, but are available in limited ratio's
3. what rpm should i be looking for on the low speed spindle to run a small (3 inch) fly cutter on 6065?
4. any suggestions/idea's/alternatives or possible issues i should look into?
*edit: note the machine is 4ft by 4foot, and uses 400w servo's, rack and pinion drive. the machine is home built, tho i am not the original builder, and is framed with heavily gusseted 6inch "H" beam gantry and 4inch "H" beam rails. it is regularly used to cut 2" thick 6065 sheet, with onsrud 1/4 inch cutters. coolant is high pressure flood using 30:1 cooltool mix
*edit2: also forgot to mention i have access to a lathe, but do NOT have access to a conventional mill!