The Workshop Progress thread 2018

Tom

I'm curious what the tool is for?

It looks like a self centering two jaw chuck which can be manually rotated (on two ballraces) and its sits in a hemispherical recess at whatever angle suite the purpose. Its just the purpose I cannot work out.

Ian P

For old fashioned die sinking, or engraving maybe. A handy thing for hand work. Beautifully made too.

Follow Tom's link to his album and the title will tell all.

.

Thanks for the clarification, Tom

MichaelG.

I followed Jason's advice and looked at your album, then Googled 'jewellers vice' and looked at images. Only a couple out of hundreds shown looked anything like yours so I added 'ball' to the search and found scores of them.

Yours looks beautifully made, presumably mostly aluminium and I can see its not easy to decide what features to add to the jaws if your work needs any.

I found an online video of a vice and engraver in use. Previously I knew nothing of the art of engraving but I'm impressed and tempted to have a go.

Ian P

TomK, as a jewellery maker used to using GRS workholding equipment, I've nothing but admiration for your work. Perhaps you've thought of this already, but some leather-faced jaw inserts would make the steel jaws kinder on precious metals and provide good grip.

Recently I removed the Chinese 4 axis Fanuc clone controller from my CNC milling machine. It's clearly a very powerful and capable controller but despite my many years working in China and with Chinese, I simply can't fathom the strong Chinglish in the manual and of course any attempts at technical support suffer from the same issue. Instead I fitted a Centroid Acorn controller from the US. Cost twice as much but has the benefit of documentation and support that I can actually understand. And unlike LinuxCNC it doesn't require a PhD in Linux and funny handshakes to set up.

I've now got my Renishaw touch probe, automatic tool setter and rigid tapping working after a bit of effort and support. Works pretty nicely and wasn't too painful to install and configure. Unlike some of the CNC controller outfits, they have been fitting controls to industrial machines for 20 odd years, so by and large they seem to be able to work with most configurations. I bought mine from a Danish reseller, thus avoiding import tax and duty (being in the EU: perhaps there's a lesson there somewhere).

Tonight I machined 2 test pieces. Both the same simple shape - 50mm square stock with a spherical concave surface on the top face. You generally machine these with a ball ended end mill but the disadvantage of these cutters is that the surface speed of the centre of the tool is zero and you end up with scuffing and a poor finish where that part of the cutter is used. The approved solution is to use a 5 axis machine so that you can tilt the tool towards or away from the direction of travel. That's not an option for me, as the present Domestic Manager won't stretch to that. Instead I thought I'd achieve a similar effect by tilting the stock at 55 degrees to the vertical, so that the end of the cutter never has to attempt any cutting.

The toolpaths are quite easy to do in Fusion 360. To achieve the tilt you simply define the Z axis at the required orientation and within reason, the rest follows.

Sure enough, the surface finish is a lot better, although there would be further improvement if I used a tool with a better (polished) edge - you can see the grind marks from the tool on the workpiece. And coolant would have washed the swarf away and prevented any minor recutting. I don't have the guards back on yet, so coolant wasn't a sensible option.

All in all, an interesting result. For surfaces that would benefit from a fine finish, this approach has potential. Obviously set up takes a little longer and the machining time was about 50% longer but each piece took under 30 minutes, so hardly an issue.

Conventional (perpendicular) toolpath. Look carefully and you can see the spiral surface finish in the middle of each track:

With angled tool. Every imperfection on the ground edge of the tool shows up!

Murray

Wow, that looks good Muzzer. I've done a fair bit of CNC machining with ballnose cutters, but only in the conventional sense. The finish I got didn't look too bad to me, but obviously not as good as yours. Doooh, didn't think of tilting the workpiece. I've got some press tooling to make for the strakes on my traction engine wheels so I may well have a go at tilting the work. Or may be I should just have a few beers so that I lean over to one side.

Andrew

Rather than use a ground (ideally honed) HSS or carbide cutter, it's possible to get polished carbide inserts for indexable tooling eg a 16mm diameter cutter with a 3.1mm corner radius. That's basically a "bull nosed" shape, as our Mercan cousins would call it. So that would give a reasonable radius to work with, albeit with a cylindrical central portion. They should have a more precise edge profile and less surface speed variation across the edge.

They would allow better surface finishes on convex surfaces and for some areas within concave surfaces. The very bottom of a dished concave surface would still be a problem. But while I am saving up for my 5 axis machine, this may be a partial solution in some situations.

The AP** inserts don't appear to be available with any significant (>0.8mm) corner radius but the Mitsubishi R390 family (different insert geometry and toolholders) are available up to 3.1mm (1/8" ). These are available on ebay and Aliexpress, so further trials will commence in a few weeks....

Murray

Edited By Muzzer on 14/04/2018 11:21:01

Murray, it would be interesting to have a link to the Danish importer please?

It was these boys. Total was 3081Kr all in which is about £358. Arrived in 3 days. I bought the upgrade license direct from Centroid as it's just a license key.

Refreshing not to get ripped off on the way into the country by both the tax man, customs and couriers. CTC Tools (HK) have a Danish warehouse too so you don't pay duties etc on their Chinese stuff - no idea how that works...

Murray

Plenty of Chinese companies have UK warehouses - HMRC have figured out how it works...

Neil

Started on the flywheel for my Vertical cross; casting was a bit rough looking at the start, ( unfortunately didn't get a pic before starting ),I have another casting but that's even worse, anyhow by the time I got through a section of chilled casting, what started out as a 4" casting ended up as 96mm OD, & still had remnants of a blow hole on the rim. The only option was to mix up some two part epoxy resin & blend in some CI filing dust to strengthen & colour match...

Apologies for the out of focus shot, but you can just make out the hard spots on the centre line......



Remains of the blow hole imperfection...



Mix of 2 part epoxy & CI filing dust applied ....



​Should blend in fairly easily...

George.

p.s. alternate flywheel... rough as, I suspect there's probably more chilled iron in this one than the one I'm using...





We'll see eventually...

George.

George

As a matter of interest, where do you get these castings from?

Jim

The RDG ones are a very good price but you have to take the good with the bad as they vary a bit, I try to buy them at a show where you have a chance to look at them and pick what looks best from the outside.

A good source of small flywheels is this seller on e-bay, he used to cast for College Engineering and Blackgates, the ones I have had from him are fine.

George, if you are still looking for a 9" spoked one then try engineers Emporium, they list 8.5" and 9.5" but don't put them on their website. Another source may be Polly/Bruce as the R*B engine has a 9" flywheel option