[David_Nolan]

I'm building a DIY cnc but I've hit a bottleneck. I want to run my spindle with a belt and already have the motor I plan to use to drive it (Vevor 2.2kw spindle) The issue I have is I want to step down the rpm which is easy enough to do because the spindle has terrible torque below 3000rpm and I want at to run at like 600rpm or in around there for steel cutting. Here is the issue...

I can't make a spindle with the correct tolerances because I don't have a good lathe. I can't custom make one because its ridiculously expensive and I can't find where to buy one. When I google spindles, all I get is motors. I found one without a motor on aliexpress but I've had so many bad experiences with ali express I just don't trust them. I'm using either R8 or MT3 tooling, so if anyone can help me out or offer some advice please do so!

Thanks.

- David

Based in Ireland.

Some extra info/queries/jargon

I did a quote, but it was what I would consider a rough quote, so when I said it was too expensive that is just my touch feely idea. I figure the tolerances will be tight for a precision custom spindle and I actualy don't know how to express tolerances for a taper or what the tolerances should be. Machinery handbook said 0.002" or 2 thou per foot but I don't know what they mean by foot. Do I give the manufacturers a tolerance on the angle of the internal taper, who knows. This is hard when your an outsider. I figure if I can buy like a R8 to straight shank adpater maybe that will work but if I jam that shank into a hole with a interference fit will I lose concentricity.

[dazp1976]

The only thing I can think of is a R8 spindle from a Sieg X2.
Not sure how strong it would be though on steel.
You would have to make your own head casting to seat the bearings like part 114 in the diagram link.
The top part of the shaft where a pulley would go is 28mm diameter I believe.


Spindle:
https://littlemachineshop.com/produc...ProductID=1407
I've seen cheaper. This is just for quickness.
Bearings:
https://www.arceurotrade.co.uk/Catal...indle-Bearings
Diagram:
https://www.arceurotrade.co.uk/machi...-List-2012.pdf


Or scrap R8 altogether and get one of those stupidly expensive BT40 ATC spindles from China.

[David_Nolan]

Cheers dude this is great... I've seen these mills cut steel, it doesn't do a stellar job but beggars can't be choosers. Man little machine shop is great

[joeavaerage]

Hi,
try this company...they have a good reputation:

China Belt Driven Mechanical Spindle Suppliers, Manufacturers and Factory - Customized Products - Jingjiangcity Jianken High-Speed Electricmotor Co.,Ltd

Craig

[David_Nolan]

Thanks man, I didn't think there was companies that offered stuff like this without having to buy other additional stuff. Does anyone know of a store based in the UK like littlemachine shop?

[dazp1976]

Thanks man, I didn't think there was companies that offered stuff like this without having to buy other additional stuff. Does anyone know of a store based in the UK like littlemachine shop?

UK is a waste of space for many things.
The only 2 that spring to mind are Arceurotrade and Amadeal.

Actually. I bought my spare Sieg X2 spindle from Sealey. Was supposed to be direct replacement MT3 but they sent me R8.
That spindle doesn't fit the 2spd geared head.
When I spoke to them they did not know the difference.... Clueless!. Hence my R8 and belt conversion on that came early lol.

That is the uk for you!!!!!!.
Just full of middlemen buying from East and selling it on. Not a clue about the product being sold.

[joeavaerage]

Hi,
the internal spindle taper is only one part of the spindle that requires precision grinding. The bearing lands and the bearing housings must likewise be precision ground.
P4 grade angular contact bearings WILL NOT TOLERATE misalignment in the slightest degree.

There are a number of Taiwanese companies offer precision spindles:

https://www.twspindle.com/
Built In Spindle LMS-S20 (CNC Lathe) - Posa Machinery
https://www.royal-spindles.com/milli...e-spindle.html

Craig