Here we go again . . . MK4

[Clive S]

OK, so I need to bore this hole out to just over 80 mm to give a nice sliding fit on the WC spindle:

This is the guy to follow with lathe work this is part three but worth watching https://www.youtube.com/watch?v=mAzCVDF304o

[routercnc]

This is the guy to follow with lathe work this is part three but worth watching https://www.youtube.com/watch?v=mAzCVDF304o

Thanks Clive. I know Keith's channel well, he does some great work.

For info he held the tool in the 3 jaw, which will have some run out, but as this is a single point tool it does not matter as such because it will still cut a circle. What it does mean though is measurements of the cutting bit (made with a mic or calipers between the tool tip and back of the bar) can only be judged relative to the last cut, not absolute. So if the cut needs another 0.25 mm taking off then that is the increment of the tool.
However, using between centres (effectively no run out) allows absolute measurements of tool stickout because it is revolving about the true centre of the bar, assuming the bar is straight. So if you want an 80 mm diameter cut you can set the tool to that distance before the cut. Of course you would still check the bore of the last cut as you proceed to be sure. Either way works.
Also I had to make a lathe carrier (to transmit the rotation) because couldn't find a commercial one that big (bar is 50 mm). I'm sure they exist, just didn't see one on a quick search and I made mine in the time it would take the postman to send one, plus it was 'free' from scrap material.

[Lee Roberts]

Here is a video showing the same boring method in use :)

[routercnc]

Cheers Lee, all good info.

Tiny update:
Drilled 3mm pilot holes ready to open up and tap to M5. These are peck drilled right through the 20 mm part using a 1 mm peck with full retract in between, and dab of oil each time the drill comes out of the part to clear the swarf. These take the leveling grub screws:



Then the part was flipped and the counter bores machined for the M12 cap heads:


Then bolted down onto the top slide using the T-nuts I'd made for another fixture. The M12 bolts are a bit long so will need to cut them down. They will hold onto the side of the spindle block which already has M12 holes in it. There are some random threaded holes in the part but they were in the piece of scrap I made the part from:

[Zeeflyboy]

really interesting stuff... keep it up!

[Nickhofen]

This cnc build porn must stop!
(Please keep it coming).

[routercnc]

Look forward to seeing the lathe work, will you be video'iiinngg it as you machine it?

OK, as requested here is a video of making a fixture, setting up, and then line boring the spindle housing . . .



Still lots to do but another step closer.