How would you go about machining this rough casting?

[Lo-Fi]

Haha! Yep, that's the kind of the I'd do

Interesting about that part. I'm tempted to do a hybrid job and machine the bottom as a separate ring to stick onto the casting. Thanks again for all the info, I'll start a Quorn Build thread shortly! And make some heavy hints to JP, of course...

What way did you go with the wheel mounting arbours/collets, out of interest?

 

[Rex Walters]

What way did you go with the wheel mounting arbours/collets, out of interest?

Not sure I understand the question.

I had to remake my spindle (long story).

You really should cut the taper on the spindle and on the arbors without moving the compound in between operations. The taper in the spindle is cut by holding the bearing box in a steady rest and driving the spindle from the chuck. I think you try to make all the arbors you'll ever need in one sitting. The goal is to dedicate arbors of various sizes to the different wheels you plan to use, so you have to plan ahead on specific dimensions.

I need to do all of that, build a base and some storage, paint (shudder), and add a couple of 220V outlets at convenient places in my shop. I should really swap out for a 110V single-phase motor for convenience sake, but I can't decide which is more effort (the 230V motor came with the UK kit).

For work-holding, I'm planning to use ER collets but would really like to see if I can figure out a way to mount a Gorton spindle to hold Gorton-taper tooling. I can grind round (or square!) tools in the ER collets but either need to make a holder for tapered engraving bits, or figure out a way to mount a Gorton spindle. Engraving is incredibly fiddly for fine work, and grinding the tools in-situ rather than in a separate holder would obviously be more precise, so I'd rather figure out how to mount a Gorton spindle if I can.

The funniest bit about getting the thing to this point is how much better it's made me at free-hand grinding various cutters!

I'm actually comfortable with free-hand grinding lathe bits and most one-off tools, but some tiny cutters and especially engraving bits just can't be ground without a T&C grinder or some sort of jig/fixture.

I'm not exactly the first to have noticed how handy a Quorn would be to grind the cutters necessary to make a Quorn! I broke a handful of hand-ground trepanning bits cutting the labyrinth seals in the spindle caps, for example.

 

[Lo-Fi]

Not sure I understand the question.

Sorry, I should have explained better! I was under the impression from the Hemingway blurb that they'd modified the design for some commercial wheel mounting system, but maybe that was just for the work holding. I know I'm going to end up getting some wheels I won't have arbors for in the future, so that's why I was thinking about what might be adaptable off the shelf. I was thinking about buying a tapered reamer and making the spindle a male taper with the arbors for mounting wheels female. That way I only need to cut the male taper accurately on the spindle once then finish up arbors with the taper reamer whenever I need them. Perfect fit assured! No need for a drawbar either - and internal thread on the spindle and a countersunk cap head would do.

ER16 looks like a good bet to me too for work holding, with accurate straight shank adaptors readily available. Seeing Stefan use his Deckel clone to make many tools, he tends to use round for just about everything anyway. Lathe tools from square stock I'm not as fussed over, I'm happy grinding them by hand.

I've had a go at the rotating table casting today. Its nasty! The material is ghastly gummy stuff and the protrusion you're supposed to make the bearing shaft out of is off centre with the rest and really quite wonky. I might save it by chopping that off and machining a nicer item out of tool steel to be pressed in maybe. I was planning to do a hybrid construction with the bottom of the T slot machined separately and pressed/glued on like yours anyway.

Thanks for the continued informed discussion!

 

[Rex Walters]

Hybrid seems reasonable, but if it's that awful, I'd just get a couple of free-machining steel drops (what's called 12L14 over here). The machining of the two pieces was pretty straightforward from what I remember. The hard part was machining the captured nuts and end-stops -- the nuts need to match the curve of the slot.

 

[Rex Walters]

I was thinking about buying a tapered reamer and making the spindle a male taper with the arbors for mounting wheels female. That way I only need to cut the male taper accurately on the spindle once then finish up arbors with the taper reamer whenever I need them. Perfect fit assured!

Did the design change? The wheel arbors have the male taper in the current Hemingway design. Seems you'd need bigger diameter arbors to do it the other way.

 

[Lo-Fi]

Not so much, it was me thinking of changing the design! More thinking required before I go ahead. Wheels I've been looking at all have 20mm bore, so plenty of internal room in the bore. Like this:



It's a little more complicated than it might be because.... Robin Renzetti. The clamping arrangement with M4 set screws (not shown) providing the actual clamping force allows precise setting of the wheel without disturbing the runout when clamping the nut down. You're also not replying on a thread being 100% true either. The assembly can still be removed from the taper and replaced as usual preserving the setting, of course. You could just use the clamping nut and pin spanner, but Robin explains in an excellent video why that can be a faff when you're setting new wheels up.

That's what I'm thinking, anyway! It's still just a sketch at this stage.

 

[Rex Walters]

It's a little more complicated than it might be because.... Robin Renzetti.

Hah! I understand that sentiment exactly.

I wish I had a tenth of that man's knowledge or abilities (take your pick). My machining skills are more of the "rough fit and gentle persuasion" variety (most persuasion via my #3 alignment tool: a lead hammer).

I'm very interested to follow your results with that orientation of male/female tapers.

The professor's design used a pretty steep taper (40° included) so they don't seize. I think the most common commercial reamers are for a Morse taper which will definitely require a bit of persuasion to remove the arbors — is that the purpose of the M4 taped hole shown? (A wheel puller, ... err, pusher?)

 

[Rex Walters]

The clamping arrangement with M4 set screws (not shown) providing the actual clamping force allows precise setting of the wheel without disturbing the runout when clamping the nut down. You're also not replying on a thread being 100% true either. The assembly can still be removed from the taper and replaced as usual preserving the setting, of course.

Whoops. Gotta learn to read first (words and diagrams).

Ignore my question. I think I understand now: the M4 set screws are for adjusting the wheels between the clamping washer and the arbor. But the primary concern is radial positioning of the wheel since the back of the back face of the wheel is positioned by the flange on the arbor. The oversized hole in the wheel mandates radial positioning. I don't understand the benefit of the M4 screws — I'll have to see if I can find Robin's video. If you have the link it will be appreciated.

If you use something like a Morse taper reamer for the arbors, though, I do think you'll need to devise some type of puller to remove the wheels. Or perhaps find or make a tapered reamer with a steeper angle?

 

[Lo-Fi]

It's buried in a toolroom tips video. Excellent content as always from Robin:

Yep, you're right on with the taper. Self locking would be a pain, so steeper like the INT series seems sensible. I've found some taper reamers that look promising, so I'll order up and give it a go!

I'm transitioning from rough fit with persuasion to engineering fit. Getting the two base castings dead nuts on, both centre to centre distance and bore size Such that they're a beautiful sliding fit even right up next to each other was a bit of a revelation!

 

[Janderso]

And I'm going to be heartbroken if Joe Pi doesn't build a Quorn after he finishes his lathe model.

I've already started the campaign, both with Kirk and with Joe. Please add your voice to the fray!

Joe has added a new level of perfection in his model builds. Incredible machinist.