small mill for machining steel. Max spend £500 including computer

[BillTodd]

BillTodd I looked up you roller nut for your mill conversion when I was wondering what would be a good low cost ballscrew alternative. Are you still using this and if so how is it going?

They're working really well, well enough for me to consider replacing the fixed nuts on my Haighton as well.

As you say, the space requirement is the main drawback. I've been eyeing Mike Everman's quad bearing design and wondering if I could use it with some compact bearings instead of my twin roller type.

Bill

[Andrew Wilding]

looks like an interesting solution. Looks like it was well covered in the thread so I will not regurgitate that here, but how would that work with large pitch (high lead) screw like the one fitted to your mill. You may only end up with one or two line contacts per bearing? I guess it is not an issue with the type of duties our mills see. Obviously you will have to post results when you get onto manufacture!


Nice job on the refurb by the way.

[Andrew Wilding]

I tried the new x axis nut out last night. Backlash was very similiar to the previous nut at about 0.0007" and did not reduce even if I cranked the nut up tight so I suspect that I need to look at the preload on the AC bearings or check for movement of the bearing in its housing.

Rapids have gone up from about 30" min to 150" min (+ acceleration increase) without lost steps so nut drag is much reduced.

I am happy with the solution. Now to make the y axis (Z does not have a fancy nut as gravity is working in the same direction ad the cutting force so eliminating lash naturaly)

[Andrew Wilding]

I have had a busy week as my second child was born on Friday! All is well and Lydia is starting to become a bit more aware of her surroundings. It does mean that I have some paternity leave and so in between changing nappies and winding I have had a bit of shed time.

I have rebuilt the mill and painted it. Here are some pics of the z assembly showing rotating nut (not pressed in in the photos)

[Andrew Wilding]

Here is a picture of the newly painted mill part assembled


Jobs I am hoping to do in the next couple of weeks:

tidy up wiring with conduit and built swarf protection for limit switches
screw and way protection
Modify spindle ratio
guards and machine mounted E stop

[M250cnc]

Hi Andrew,

Looking good

How long did it take to design and build the Z axis ?

Phil

[Andrew Wilding]

Hi Andrew,

Looking good

How long did it take to design and build the Z axis ?

Phil

Cheers. Design was carried out during daydreaming on the train and manufacture two or three saturdays of pottering in the shed plus a bit on the computer to purchase belts and bearings etc.