Here we go again . . . MK4

[routercnc]

There are a few jobs to do on the main spindle housing. Boring pilot holes on both sides of the block:


Then the pilot holes for the M8 taps for the spindle clamp brackets. Spindle block is so big I had to get inventive on the fixture to machine these parts:


Then onto the tapping 16 off M12 taps and 4 off M8 taps - took a while !


Quick assembly check:


Then noticed that some of the bolts were loose on the current machine. Wondered why it had been chattering more recently - was worried the small 15mm profile rails had worn, but then spotted this:


So I had to dismantle the Y axis and tighten them up. 2 bolts had come right out, and one more was loose. The rail has also lost a bolt. I guess that is what happens if you ask a machine designed for wood to plough through endless 20 mm aluminium plate for months on end. Used loctite and tightened them back up. Also doesn't help that on 15 mm rail they use M3 bolts which are very small and you can't put much torque on the heads.

Then onto making the spindle clamps:






Although I've got to bore out the spindle hole on the spindle block, I thought I'd check everything was going to fit together. Aligning first rail to master datum:

(note the rails are slightly too long - have marked them up for gentle grinding back to length)

Dialing in the second rail, ref the first:



Then checking the vertical alignment showed that the 2nd rail was ~0.05-0.1 high towards one end. The large side plates they sit on will need the M12 bolts loosening and knocking round slightly when this goes together for real.


Coming together:


Then discovered a problem! The whole assembly is ~2 mm to big! The plate at the top of the photo should be flush with the side plate but is clearly too high.


Bit of head scratching, and checking the drawings couldn't find anything I'd made which was out of spec. Then checked the profile rail and carriage and they were ~2 mm taller in total than the drawings I'd down loaded from Hiwin. I know it has been mentioned on this site many times but check the hardware before committing the drawing and making the other parts !
Luckily this is easy to resolve, just take ~2 mm off one the side pieces and everything will be back in line again. I'll leave that till later because everything has to be set up to get it all very parallel otherwise the rails will bind.

Onto making parts for the lathe to bore out the main spindle housing to final size . . . more to follow

[Desertboy]

Damned fine work there!

[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: