The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)

[awemawson]

O ring ordered 

I made up a dinky little M4 slide hammer to try and get those two threaded dowels out. Only partially successful so far.

The first one shattered so must be very hard, but there was enough internal thread left to get the butt out. The second one is resisting removal so will have to wait until the morning.

(They are 6 mm x  30 mm tapped M4)

[Pete.]

What's next? Turn a pinch collar to grip the OD with a m4 thread in the end for pulling on?

[awemawson]

A good idea Pete but not necessary as THE DOWEL IS OUT 

Usually you can heat things up to get a bit of differential expansion, but I didn't want to heat the casing up or it might distort, but then I remembered my Freezer Spray - used to identify intermittent heat problems with electronic components it allows me to dibble just a bit of the liquid onto specific places. Well the dowel has an M4 female thread, ideal for the straw 

It took a couple of freezing sessions, but then very slight movement (Sharpie mark on dowel as indicator) and I knew it was mine.

(The frozen photo is posed - obviously by the time it came out it was nearly the same temperature as the casing block)

So now the next decision - oil or grease lubrication? Suggestions please.

[awemawson]

The next job was to make some replacement dowels - simple enough as I happened to have some 6 mm precision shafting. From a dismembered printer I suspect.

I decided to make them shorter at 20 mm (originally 30 mm). With the section that I milled off to accommodate the Turret swarf guard one had to be shorter anyway, and frankly the length doesn't add to their ability to locate the two half of the gear box as they are in shear in use.

The shafting must have been surface hardened, as although it's core is still pretty tough, starting the parting off, even with an inserted indexable parting tool was 'interesting'.

They are a nice pneumatic 'pop' fit 

[awemawson]

The bearing and seals arrived in today's post so I could get on re-assembling it while the pottery kiln cooks a bit and dries out (hopefully).

Just reversing the sequence of pulling apart so not frightfully interesting. I packed the bearings with high temperature lithium grease in the end as that's what I used on the straight ones.

Still missing the large O ring that seals the cover for the taper roller bearing end float adjustment, but I mounted it up anyway and ran it a bit to 'run in' the bearings before final adjustment.

[awemawson]

Big O ring still not arrived so I decided to modify the drawing for the spanner that I made for the axial powered tooling to incorporate an opening at the 'other' end to fit the locking flats on the 90 degree holder.

After an initial oddity in Autocad where an unwanted circle wasn't displayed, yet was in SheetCAM, solved by "Eagle Eyes" David Judd who spotted a minute dot in the drawing that for some reason, like a collapsing black hole, the circle was compressed into - the spanner is made.

Actually it took more fettling than it should have - my drawing obviously wasn't spot on

[awemawson]

At long last the rather odd sized O ring arrived - (well actually a bag of ten of them !). I strongly suspect that the original would have been fine, but whilst things are apart it's best to do a proper job I reckon.

So, swiftly the capping was re-assembled and the unit re-installed. It's running a 'soak test' as I type.

As far as the turret goes all that remains now is to be brave enough to replace all the tin work - superstitious I know but I reckon that the chance of the turret giving me more problems will probably increase tenfold when the covers are back on !

[awemawson]

This morning I re-installed the tin work on the turret. Went reasonably well considering the contortions needed for screw access 

So all back together and I did a trial test of the powered tooling, which revealed a nasty rubbing noise that hadn't been there before the panels went back 

Rubbing noise associated with the rotation of the powered tooling - drive shaft or drive belt fouling 

So the smallest of the covers that covers the powered tooling shaft and drive, which fortunately can come off without disturbing the other ones, had to be removed. This revealed that the end of the hub of the toothed belt pulley on the shaft was rubbing on the vertical face of the cover. I'm not really surprised at this, as this panel had obviously suffered badly in a crash under the previous owner, and I'd had to rather guess what shape it needed to be !

Need to decide on a work-around, but not now, it's time for lunch 

[awemawson]

Fortunately, by elongating the 6 mm mounting holes slightly, and biasing the cover towards the tail stock  as I tightened the screws, I was able to get just sufficient clearance for the pulley hub not to rub. It is mighty close though.

If my sheet metal work skills were better I'd be tempted to make a completely new cover about 10 mm longer to give adequate clearance, as this one is pretty bashed about and wouldn't win any beauty contests ! But it is a very awkward shape to fabricate with lots of odd angles.

I've heard from the lost wax caster - apparently both drive dogs have come out OK, so that's good news but I've yet to see them.

[vintageandclassicrepairs]

Hi Andrew,
What about cutting out the damaged section and welding in a new piece?

John

[awemawson]

Yes I gave that approach serious consideration before I started trying to flatten the damaged bit, but frankly the whole thing is distorted. I assume that it came into contact with the tail stock sometime in its history.

I'm going to try and make a drawing of it and see if I can work out a bending plan. I suspect it'll be easier to make several sub assemblies and braze / spot weld them together. Looking at it, the original is made from two bits fixed together but increasing to four or five will help.

[awemawson]

The plan today was to measure and draw up a model of the cover, print it on paper, glue it on card, and try it. That plan fell by the wayside as I tried juggling multiple A4 print outs.

Hang it I thought, plot it on the CNC Plasma Table tying a pen on it - then, no hang it just cut it 

So I measured up the first part of the cover - the rectangular part that actually covers the belt - zapped it into Sheetcam and cut some steel, bent it up, then realised I'd marked and bent on the wrong side - it's inside out 

Never mind, it'll be a practice piece for when I MIG weld it up .

Second cut on the CNC plasma table, then bent it the right way this time  I see I've got the angle of one lug slightly wrong, so I've corrected the drawing but I don't actually think it matters much - anyway I could patch a bit in when welding up if it proves fatal.

Trying it out on the machine it fits at least as well as the original - no fixing holes yet so just wedged in with a screwdriver ! NB This one is 10 mm longer than the original to give extra clearance for the pulley hub.

So I think it probably is feasible for me to make another cover, it just might take a few iterations 

[awemawson]

I did actually make a third one incorporating the missing bit and then started on the second section. Just a strip folded with some interestingly close together folds that involved modifications to the folder.

Fit up is not fantastic, but it should be OK for MIG welding if I can remember how 

Just the last little triangular bit to do now which probably is best done when the rest has at least been tack welded.

[awemawson]

Time to glue it all together. I dug out my Migtronic KDX 250 MIG welder that is loaded with 0.6 wire but try as I might I could not get it set up. The 'burn back' circuitry and control don't seem to be working - something to fix when a RoundTuit  comes along ! So I had to resort to the Butters AMT  3205 which is loaded with 1 mm wire and better suited to welding 6 mm plate.

So a few practices on offcuts and also the prototype cover that I bent up inside out, showed that with care it was possible, but mighty easy to blow a hole - this welder cheerfully blows hole in 6 mm plate !

Quite a bit of tacking a bit, bending to shape, tacking a bit more until there was enough done to try a test fit. Not too bad at all, just a trim off one edge. Then I had to create the triangular feature. The original cover was rather distorted, and a packing piece had been fitted to jump a gap, so by a little bit of re-design I was able to get a reasonable fit without the packer.

Then it was a case of grinding back the welds - not all the internal bits are accessible to the grinding disk but I don't suppose it matters much.

Then numerous fitting and removing and marking and drilling and fitting and marking . . .well you get my drift . . it was great fun transferring the holes from the turret onto the cover. I couldn't just copy the original as not only was it distorted, but the new cover leave 10 mm more clearance for the powered tooling pulley (which was where all this began !)

Eventually all screws were able to be fitted, and now it needs a good final clean up and a few coats of paint.

[tom osselton]

Nice job!

[awemawson]

So last night the cover got a bit more tidying up and rubbing down, then this morning a rattle can coat of zinc rich primer on both sides while poor old Hugo the Vizsla  succumbed to the sedatives he had to have prior to a vet visit (swollen toe not responding to treatment).

Once Hugo was Zonked he was taken to the vets, given another jab that totally knocked him out, and left for examination while I had my hair cut. Nothing showing on x-ray or probing so stronger antibiotics for three weeks and rather a lot of spoiling.

This left me free to spray the first 'top coat' of RAL9001 on the cover which is now drying. Went superbly until a fly decided to fall on it, upside down with wings spread ! Carefully removed with pointed nose pliers, I hope the paint self smooths as it dries, otherwise there will be an impression of a spread eagled fly for posterity!

[awemawson]

Having the newly re-commissioned  kiln to hand I decided to accelerate the drying of the first coat  by cooking it for an hour at 90 deg C. To avoid radiant heat damage direct from the element I used the 'simmerstat' control on the kiln to set a very low rate of heating - this switches the elements on and off with a period of a second or so, and hopefully avoids them actually glowing at this low setting. Can't be sure as the door is interlocked with the power.

I got a very slight bleed from the metal loaded filler I'd used to fair the cover in places, so having sprayed the top coat while it was slightly warm, I left it over night to dry. Thankfully the dead fly damage barely shows.

This morning I put it back in the kiln at the slightly reduced set point of 70 deg C and will leave it for several hours. Hopefully this will get the enamel as hard as the rest of the turret cover that I left for two months before re-fitting.

[hermetic]

Fly damaged paintwork is one of those things that is really annoying at the time, but a few days later, you have forgotten it ever was a problem! look at it from the flys point of view.................Seriously, I find I have to curb my desire for perfection because it can drive you (me!) to many hours of work that is completely unrecognised by anyone, including yourself, even a few hours later. More to the point, what is this metal loaded filler you mention, I have a little job that might benefit from some of that.This is still one of the most entertaining and intelligent threads on the forum, and I must admit a modicum of addiction which I am trying to curb by not making Mad Modder the first forum I check every night after work. I am having some succes with this.Good luck with it Andrew, and keep it coming!
Phil

[awemawson]

Phil, Thanks for the kind words. The filler is  Isopon 'METALIK' , but be aware - my tin is running out, so twice I've tried to buy a replacement on eBay (from two different sellers) and each time I was sent another Isopon product intended for repairing cosmetic damage to aluminium rims 'Isopon Alloy Wheel Filler', and when I contacted them they both said that their bulk box was wrongly labelled (and keep the tin). It may be as good for all I know but it's not the same !

So after a few hours cooking I let the new cover cool to handleable temperature and re-fitted it, so that's a rattle can of zinc rich and two sprayed coats of coach enamel in 24 hours and as I baked it it was easily hard enough not to mark as re-fitted.

Glad to be able to report that the drive shaft no longer rubs on the cover - but then it shouldn't as the new one has an extra 10 mm clearance 

Certainly a technique to consider in  the future as usually it takes weeks for coach enamel to fully harden.

[tom osselton]

Looks dam good!
I was watching Forged in fire last night and one guy had hammer marks that were too deep on his blade and used powdered metal mixed with epoxy that worked good even in the bone chopping test!

[awemawson]

Thanks Tom

Today the postman brought me    THE BRONZE DRIVE DOGS 

They look splendid as cast - obviously they will require a little machining, at least on the bore, but the actual teeth mesh beautifully with their opposite number on the machine.

I was surprised to be able to see the actual build lines from the 3D printer, as crisp as the original though more visible due to the colour.

So I'll probably bore you to death with the fettling and machining over the next day or two

[PekkaNF]

.....

So I'll probably bore you to death with the fettling and machining over the next day or two

PLEASE!

There are way more nasty ways to go....

[b4dyc]

So I'll probably bore you to death with the fettling and machining over the next day or two

You can keep trying but we are made of tougher stuff here 

[tom osselton]

It’s never boring watching posts there is always something that gets stored in the back of the brain!

[hermetic]

Bore us to death? I am waiting for the youtube channel! Today I have been mainly welding!
Phil.