Here we go again . . . MK4

[Chaz]

Agreed, some of the best on this forum IMHO.

[Nickhofen]

Very nice work.

[Lee Roberts]

Looking great, I like the design for securing the spindle not seen it done like that before, I agree that your work is on par.

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

[routercnc]

Looking great, I like the design for securing the spindle not seen it done like that before, I agree that your work is on par.

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

Thanks all, and thanks Lee. The clamps only hold the spindle to the back of bore, so it is not all round support, but should be good enough. As an upgrade if I make a new spindle this will mount via the lower flange to the base of the spindle block, which is arguably a bit stiffer. The tapped holes and counter bore area are already machined so it will just drop straight in.

I've not done fly/line boring before so am learning as I go. May video it, see how it goes. Will have a lot to think about to avoid crashing the lathe.

If fly/line boring is new to anyone I'll post a few pictures up soon to show how I'm going to approach it.

[routercnc]

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


To give you an idea what is required here is the finished fly-boring cutter mounted on the lathe. Chuck is removed, an MT4 dead centre put into the head stock end, an MT2 live centre (rotating on bearing) put in the tail stock end, and drive provided by a long bolt from the drive flange running through a lathe carrier (lathe dog). This may look precarious but it has been done like this for years:


So here is the walk through to get to that point. First off I sketched it out:


Then I needed a single point cutter so started with an old 10mm HSS cutter:


Then marked the tool, roughed it out using an angle grinder with an inox blade. Then used the bench grinder to ground the required shape. Still a bit of finessing required:


Marking out the tool carrying bar with 2 scribe lines - one in the middle (where the tool, clamp bolt, and adjust bolt will be), and one further down where the edge of the vice will be. This is to keep it aligned when machining the features:


I needed to make a rotary alignment tool (don't have a rotary axis):


Setup for first op:



Then used the alignment tool to rotate it 90 degrees:


Aligned to edge of vice jaw:


rotated for 2nd op:


rotated again for 3rd op:


Over to the drill press for the dia 10 pilot to 40 mm depth:


Then reamed (very slow, lots of oil):


Holes tapped:


Assembled and checking the fine tune screw was going to advance the tool in the range I needed:



Mounting between centres:


Then onto the lathe carrier:








The last part to make is a fixture to hold the spindle mount in place on the lathe cross slide. This will bolt down onto the T-slot nuts, and bolt up into the underside of the spindle block using the existing M12 tapped holes. The key feature is that it will have M5 grub screws at each corner to provide adjustment vertically (bore centre MUST be aligned to lathe centre height), and to provide adjustment in tilt in 2 directions. Essentially a tramming plate to get it all lined up. Here is the CAM:

Flip side will be counter bored:


Machining under way:

[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!