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

[awemawson]

I've bitten the bullet and ordered a 60 mm slice of 170 mm EN24T so no more food until the end of the month 

Now I'm working on how the devil I'm going to be able to lift the 47.2 kg chuck off. On that side of the lathe there is only a 30" walk space. No strong points above the chuck, and the gap from floor to lathe base is too small for the wheels of an engine crane.

One possibility is a jury rigged gantry rigged across the lathe from that walk space to an even smaller one at the rear.

Another possibility is a home made 'cantilever crane' with it's jib counterbalanced by lumps of concrete  and able to operate in the 30" walk space.

It would be nice to make something more 'universal' as lifting can only get worse as anno domini pass 

[awemawson]

OK I may have an 'easier to engineer' solution:

By making a custom 'fork extension'  for my  Hyster 2.5 ton fork lift truck I may be able to come at the lathe from the headstock end (all the cupboards and things there are on wheels anyway) and project the extension over the lathe down the Z axis. Given a suitably strong net sling for the chuck the fork lift can do the raising and lowering, and if I slide a pole 'up the spout' of the lathe and through the chuck as a back stop hopefully accidents can be prevented.

It will need to be a 6 foot long extension at least - probably some scaffold tube with custom fixings to the existing forks. I'll do some tests but I don't suppose 6 foot of scaffold pole will object too much to 47 kg bouncing on it's far end !

[Pete.]

If you have any 2" box section I'd weld a base plate on it and knock up a bi-fold davit arm hinged at the top. Bolt the post in front of the sliding doors and swing in the arm with a small cable winch on it.

[awemawson]

Another avenue to explore Pete 

It'll mean bolting a socket down to the concrete floor - I'll explore the geometry and see if it's possible to swing in round for lowering - as you know it's a tight space !

[Pete.]

That's why I propose a bi-fold arm. So long as it's strong enough to carry the weight at full reach it'll swing the load anywhere from full extension to right up to the post.

Come to think of it, I might have a 6" box section post at work.

[mattinker]

Hi Andrew,

A tight corner! It's the endless making things to make things syndrome! Love it most of the time!

Cheers, Matthew

[awemawson]

Well it helps to sleep on things 

I've come up with what I think is probably a much better solution: The Beaver TC 20 has MASSIVE M30 lifting eye sockets in it's equally humongous base casting, two of which are just inside the sliding door. Using Pete's suggestion of a bi-fold davit arrangement, if I build off a  substantial plate bolted to these two mounts I don't think there'll be too much problem with two point rather than three point mounting. OK the plate will have to sustain significant torque with the jib extended and 47 kg dangling on it - but hey they are M30

Now in my mind I have something like the hoists used to remove mobility scooters from the backs of cars - darn me I gave one away a few years back - but they will already have the suitable articulation pivots and linear actuators.

This way the whole shebang can be fitted and removed by just undoing two (admittedly large) bolts.

So the hunt is on for a redundant mobility hoist or other such thing so please keep your eyes skinned !

(Picture is of the sort of thing I'm looking for, sadly not one that I yet have!)

[awemawson]

So this afternoon I made a 'proof of concept' wooden mock up to help me visualise the various lengths of arms and angles involved.

Just a fairly rough bit of carpentry - the final version will be welded together substantial chunks of steel with various reinforcing gussets.

. . .but it helps me see if it will work and I think that it will 

[awemawson]

Time to go from'proof of concept' to a working prototype, so I drew up the base plate in Autocad and prepared it on Sheetcam to cut on the CNC Plasma Cutter.

It was then that I realised none of my offcuts of 6 mm MS plate were big enough to cut the base, which is approximately 1 M x 150 mm. No problem, I have a stash of sheets in my container. Third one down in the layer was a full 1.5 M square, so a bit of huffing and puffing and the top two sheets were removed (6 mm plate is bally heavy to manhandle!) and I walked the chosen one to the door awaiting attention from the forklift. Plate grab suitably attached and I moved it to the welding shop, laying it on the pump up trolley. This lets me get it overhanging the plasma table, and a few more grunts and puff got it place.

I've cut the base plate with a rectangular hole  to receive the fixed upright, so that I can weld both sides of the plate. I also cut four reinforcing fillets for this upright, but I fancy they may not be large enough. At least in the fore and aft direction I can put a much larger one perhaps

Picture shows bits temporarily held by magnets while I chew over ideas!

[Pete.]

So this afternoon I made a 'proof of concept' wooden mock up to help me visualise the various lengths of arms and angles involved.

Just a fairly rough bit of carpentry - the final version will be welded together substantial chunks of steel with various reinforcing gussets.

. . .but it helps me see if it will work and I think that it will 

I must confess that I envisaged a horizontally-swinging bi-fold arm, rather than a luffing gib. Either would work just as well but with the horizontal arm you don't need anything to pivot on the post axis.

 

[awemawson]

Pete, it will need to 'take the strain' giving upwards lift before the chuck bolts are undone, and similarly when refitting to set it co-axial hence the jib construction which avoids having a hoist fitted as well.

If however there is room to fix a compact hand operated winch on the end of your arm system it might simplify things !

[vintageandclassicrepairs]

Hi Andrew,
A vertical rib length ways along the 1.5m to form a virtual angle iron,  plus a couple of ribs at 90 degrees to the long rib near the post and the holding down bolts would help stiffen the base and make it resistant to twist ??

John

[awemawson]

John yes the base will want to twist - I've planned ribs on the underside

[smiffy]

If you need to fit a hoist ,have a look at ceiling mounted disabled people hoists on our favorite auction site. They have a very nice 24 volt dc motor fitted to a reduction box and small winch drum which takes a 40 mm wide webbing strap rated at 200 kgs . I have one which I was going to use in a similar set up  The whole unit is about 9 inches x8 inches x 6 inches When I get into the work shop I will get some photos  There is also a second motor and gearbox to travel the unit across the room in a track the same as used on sliding doors and they have a built in battery pack and remote control unit They often come up for very reasonable money .  Mike

[awemawson]

Mike yes please photos:

If I can source a suitable winch / hoist then I'll go with Pete's horizontal arm version as it has several advantages, and even better if I can source a hand powered version as it then becomes entirely self contained. All the cheap ones are what I call 'ratchet winches' where to reverse them you flip the pawl of the ratchet in the opposite direction and my experience of them hasn't been good. They tend to jam in one direction and anyway are rather coarse in their positioning - OK for removing the chuck - not so good putting it back.

What I really want is an affordable 'Worm Winch' - these have the advantage of being not only fully reversible as the worm self holds, but enable far more precision in movement. But they are an order of magnitude more expensive 

Measuring up this morning I find that I have a full 12" clear above the chuck so enough room to do it given the right winch

[smiffy]

  Photos of hoist winch and travel motor

[awemawson]

Thanks Mike.

I've actually found what looks to be a suitable worm operated hand winch - a bit pricey but there you go 

Should be here on Monday - I've opted for webbing rather than wire rope.

[kayzed1]

Not a big job to fit a motor to that 

[awemawson]

True, but electrics over complicate it. Stay mechanical and no need to rig up a power supply !

It's for 'once in a blue moon' use  and I feel that the total control turning a mechanical handle gives is well worth the minor effort.

[awemawson]

Much to my surprise the winch was delivered this morning so I've been able to get on with a few things:

A/ I made up a taller 'main mast' - this time 42" tall to use the headroom over the chuck

B/ I cut the 'Bi-Fold' arms - conveniently from the previous shorter mast as each are 15" long

C/ I drilled the 12 mm pivot holes the the bi-fold arms and made up 'anti-crush' tube for inside the box section (it's 3 mm wall but best to reinforce it)

D/ I made up a pair of pivot brackets to weld on the mast but decided that they were too wimpy

E/ I re-drew the pivot brackets so that they encircle the mast with a 6 mm x 10 mm band

F/ I made a tab to weld on the end of the far arm to accommodate the width of the winch base then drilled and tapped M8 to fix the winch in place.

I still need to convert the base into a box beam, weld on the mast and fit reinforcing fillets, and make and fit a roller for the lifting webbing on the far end of the end beam.

[awemawson]

This afternoon I made and fitted the roller / spool thingy that the lifting webbing runs on at the end of the outer arm.

I cheated actually as when looking for suitable round stock I found something I'd chopped off some mechanism some time in the past that already had a spool shape in it! I just had to turn it to length and sleeve it down to 10 mm !

Bits needed chopping off the box section to mount the spool and then it was just a case of drilling the remaining vertical cheeks and putting a bolt in (yet to find one of proper length.

Then re-assembling the winch onto the arm and fitting the webbing it was ready to test. Finding a 56 lb weight I  hooked it on and wound it up and down about 2 foot.

Cranking the handle there was an alarming graunching noise in a couple of places, and examining the gear on the handle shaft there is already visible wear and it looks horribly as though it's made from aluminium alloy - surely not 

OK gears have to wear together in but heck this is lightly loaded and  has only turned a few dozen turns - it can't be right 

56 lbs is about 25 kg and this winch is rated at 170 kgs   

[Sea.dog]

That's not looking too promising.

[kayzed1]

I think i have 24v wheel chair motor/gearbox in the shed!

[Muzzerboy]

Looks as if you may doing some unintentional self-hobbing there. 

[awemawson]

It can't be a perfect mesh anyway as it seems to be a straight cut involute gear mounted at a slight angle and meshed with a worm gear.

Maybe the two will wear in in time to a happy relationship having knocked the high spots off each other !

I'll add another 56 lb weight tomorrow, which will bring it up to my expected full load, and wind it up and down a few times, but I will re-grease the gears first.