Basic questions about wax chucks

I have been reading about wax chucks in de Carle's Watchmaker's and model engineer's lathe with a view to upping my game, especially in turning and finishing components on a smaller scale than I am used to.

One problem I have been having is facing and finishing my clock wheel blanks. In the past I have made wheels out of brass sheet and turned them to the right diameter using a mandrel. The sheet is of uniform thickness and well finished so it has not been necessary to skim the surface.

Cast yellow brass sheet, which I am using for antique restoration because of its colour, is a different matter. Not only is it rough it also needs work hardening by hammering. Any blanks made from this need turning not just on their edges but also their surfaces and when they are very thin holding the work becomes tricky.

I am now thinking that a wax chuck might help. My understanding is that these have to be made of brass (not sure why) and that shellac is used to attach the work.

My questions are:

- is there a practical limit to the size of work which can be held this way as wax chucks seem to be very much a watchmakers' thing?

- how smooth does the surface of the work need to be for it to adhere to the chuck? Would a piece of rough cast brass stick? or a freshly hammered piece?

- is the chuck intended to be somewhat sacrificial? One operation de Carle discusses seems to involve cutting right through the disc, which would seem to risk damaging the chuck. It that perhaps why they are made of brass, so as not to damage the tool?

- I can see why shellac is such a good material; it is reversible and sets slowly as it cools, allowing the work to be centred and pressed on nicely as it is doing so, but are there any more "modern" ways of sticking the blanks on which are as good to better?

My wife, Deborah, needed some wooden buttons for her knitting project, so I made some from a fir tree we had chopped down in the garden, and was seasoning in the garage. I made such a chuck from aluminium bar, about 50 mm across, and turning a recess of about 3mm in one face. Filling the recess with 'hot glue' I stuck on the button blank and let it cool. I found that I could carefully turn a presentable button in this way, which could be levered gently off, and reversed the process to face the other side, and several others followed.

Don't be afraid, experiment!

Hi Nigel

A modern technic for cutting wheels is to use an aluminium arbour and to glue the blanc onto it with super glue. it is then removed using a little heat. Have a look at this video by clickspring which explains their use. **LINK**

Mickyt

Hi Nigel,

I've made my own was chucks from aluminium and attached parts with superglue. You can give them a light facing skim before attaching the part to ensure everything is square. I suppose they are slightly sacrificial but you can just face them off and start again.

Steve

+1 to Geoff's suggestion, don't be afraid to experiment with modern glues. The old-timers used what they had, we can use what we've got. I'm partial to super-glue; the bond is strong and can be destroyed by heat or acetone (nail varnish remover). The largest I've held was a 6mm Aluminium plate roughed octagonal and then turned to a 160mm diameter disc.

I'm writing from the perspective of someone doing relatively rough work on relatively large objects. Watchmakers might disagree; possibly Shellac is ideal for their processes - sticky enough to allow a period of exact centring before it dries strong enough to allow turning. Super-glue might be too fast, other glues too messy, and - maybe - hot glue too weak.

Sacrificial 'chucks', ie a rod with work stuck on the end, or other made-for-one job work-holding isn't unusual. I always use Aluminium because it's much cheaper than Brass. When de Carle learned his trade, Aluminium was expensive, but he may have had good reason for suggesting Brass, for example Shellac might bond to it better. I don't know.

How smooth? Generally smoother surfaces make for a stronger bond, but it only needs to be 'good enough'. Perhaps more important than surface finish is cleanliness - the slightest trace of oil is bad for most adhesives.

Older books are often a mix of first-class advice and obsolete practice. It can be hard to disentangle which is which. This forum is a good place to ask: there are several members experienced in your line of country.

Dave

Hello Nigel,

I have used aluminium and even mild steel for a "chuck". This is bolted onto a faceplate for the turning operation. I use just straight shellac. Although the real Tubal Cain does recommend mixing in some beeswax with the shellac. Strength of bond has never been a problem. So I expect the modern version of this technique would be just as trouble free.

I don't like cyano type glues because the fumes upset my eyes. Shellac is rather comforting and old fashioned!

Andrew.

Here is a thread on wax chucks **LINK**.

All great tips, thank you. Clickspring's videos make things look so easy that I don't know whether to despair at how little I know or be enthused by what is possible. Having once accidentally stuck my fingers together with it I have a bit of an aversion to superglue but I like the idea of using aluminium in the way he does.

I have just been stripping down my Cowells lathe (taking off the cross slide and replacing it with a manual tool rest) in readiness to start practicing using a graver.

I recently watched a video of Roger Smith talking about how his watches are made. There were a few shots of a guy in the workshop manufacturing tiny parts on a fancy CNC mill. The parts to be machined appeared to be stuck to a base plate using shellac.

It struck me as quite anochronistic using such an ancient substance with 21st century equipment. It obviously has some advantage over superglue.

I also don't like superglue fumes and might try shellac.

Isn't there more than one type of shellac? I think it's the black type but I may be wrong.

Steve

Hello Steve,

The stuff I use is in the form of brown flakes. It was used in making the cement for fixing the caps on GLS light bulbs. I liberated a coffee jar full some 20 years ago and I still have enough to last me out.

Andrew.

These old glues have their advantages. I am more a woodworker than a metalmaker and the old hide glues have great properties with their two stage set - a weak one as they cool quickly and a stronger one as they dry slowly. Modern glues tend either to set rigid immediately allowing no time to adjust or take a long time to set at all, making clamping more difficult.

Edited By Nigel Watts on 29/05/2019 16:08:31

One tip is to make the chuck back so you can relocate it easily concentric in the lathe, and cut a series of concentric narrow grooves in the surface to aid with locating circular parts. Also of course a true hole in the centre for a mandrel.

I have experimented with carpenter's knotting, which is shellac in alcohol, but you need to use a lot, let it dry before sticking by heating the chuck and the work. Can be done but don't rely on it!

Superglue works well, but fumes are an issue - I have read that just boiling the whole thing in water may weaken the bond sufficiently rather than heating more aggressively with a torch.

I wonder if one of the modern "sticks like ****" building adhesives might be worth trying?

Also as Geoff suggests above, glue-gun glue should work.

Maybe the clue to the original material is in the name - sealing wax?

That's interesting Nigel. I bought some light burr type veneer to finish a deck on a model yacht. I bought it from a furniture restorer who suggested hide glue and I wasn't quite sure why. She also said contact would be ok but positioning would be tricky and I am would be worried about the glue being flat enough. Water based glues would be out and I would only use epoxy if I had a vacuum bag set-up which I don't.

Perhaps I should go back and get some hide glue but I seem to remember there were two types?

The veneer will be sealed with multiple coats of yacht varnish so I am not too bothered about the water resistance of the glue and the boat would only ever be out on the water for 2 or 3 hours at a time and then fully dried off.

What do you think and sorry about the thread drift?

Tim

Nigel,

Modern wood glues give you quite a choice of open time, if you use Resin based such as Aerolite 306. Cascamite is wasteful since it is a one time mix, too much and you throw the surplus away. West System has different hardeners to give positioning time as did Aerolite.

On metal, superglues are fine for me, I do not find the smell a problem.

Edited By KWIL on 30/05/2019 19:47:33

The traditional method of veneering involves hide glue and an iron. Both surfaces are coated in glue, the veneer is laid on the substrate (by which time it has cooled and lost much of its tack), then the veneer in dampened, the iron applied and the veneer pressed down with a veneering hammer (not really a hammer at all, more like the thing you scrape your car windows with), squeezing the surplus glue out and getting rid of any air bubbles - not unlike how you use a wallpaper brush.

The modern alternative, unless you use contact adhesive, involves using a press as you say. The beauty of the old approach is that once the glue cools it has enough track to keep the veneer in place until it sets. The other advantage of hide glue is that it is reversible (with heat or damp or both). I have been repairing a marquetry table with hide glue. I made a little mini iron-shaped bit to fit into a tool designed to melt shellac, which works quite well.

Nigel