# How would you go about machining this rough casting?



## Lo-Fi (Aug 4, 2021)

This thing is a swine:






Print attached.

The part is gunmetal and rather "gummy". This is a replacement as the orignal had a massive void in it _and_ I messed it up when my setup moved. It tilts on the M8 through hole and has a rotating fixture that sits on top running in the M14 hole. The curving bracket protruding to the side is simply for graduations, not a working surface. As mentioned on (my) drawing, it's critical that the through hole and vertical hole are perpendicular. The large 45 degree chamfer is a working surface and must be exactly conentric and true with the 14mm bore. Yes, the pointer makes it a collosal b****** to hold.

Just spitballing really. What would you attack with a file? How would you hold? What surface would you bring in first? Mill or lathe? How would you ensure alignment? Face plate, 4 jaw or fixture? Order of ops?.... Shoot! I thought numbering the various "flat and complanar (hahahaha)" surfaces would be helpful in discussion.

As far as relavant tools go, I have a Myford lathe, Bridgeport, rotary table and Wohlhaupter boring head available to me. Clamps, Kurt clone and the precision vise pictured that fits in the Kurt jaws can be taken as read.

If you're curious, it's a part from a Quorn tool and cutter grinder. I have pics and will do a write-up on the entire build in due course. It's proving to be huge fun!

Props to Hemmingway Kits for supplying the replacement part. I bought the kit from ebay years ago as an "it's crazy cheap, will build one day" buy and they were still happy to supply the part to me for a very reasonable price.

Thanks for reading!


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## markba633csi (Aug 4, 2021)

I would make fixturing with blocks of wood, since there are so many curved surfaces
-Mark


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## SLK001 (Aug 4, 2021)

Clamp part in vise and mill flat face 1 and 5.  Take small cuts as this pass has the least support.  
Flip the part over and then mill face 3, 8 and 9.  
Clamp on faces 1 and 3 and 5, then mill faces 4 and 7.
Flip the part and again clamp on faces 1 and 3 and 5, then mill faces 2 and 6.

P.S.  Only looked at your photos, not your drawing.


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## Rex Walters (Aug 4, 2021)

Lo-Fi said:


> If you're curious, it's a part from a Quorn tool and cutter grinder.


Apologies if this sounds snarky, but have you tried following the suggestions in the booklet that accompanies the drawings from Hemingway?

They sufficed for me, though I don't remember exactly the sequence I followed.


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## Lo-Fi (Aug 4, 2021)

I have the book by the good professor, but things have moved on since the 70s when the lathe was the only machine tool in the home  shop. Some of the setups are truly diabolical! Other components could have taken days of faffing about, where the Bridgeport and boring head make accurate, quick work of it... This part, however... I can't help but think would have been better manufactured with the pointer as a separate part. The Hemingway drawings are tempting, but expensive, and also not for the version of the kit I've got, though I believe this particular part is unchanged. I've also adapted to work in metric.

Wooden fixtures sound interesting for initial work holding, and that's more or less the sequence I used the first time. It worked, then I believe a drill snagged in the void in the casting I didn't know was there and ripped the thing subtly out of alignment. I didn't realise until way later! 
The most tricky feature is that 45 degree chamfer. It pretty much dictates being done in the lathe with the pointer heading towards the headstock and getting right in the way of any sane workholding. If it weren't for that, I'd do everything in the mill. As the part was junk anyway, I finish bored the 14mm hole, then made a tight fitting mandrel in the lathe to accept the part so I could run the chamfer. It wasn't as accurate as I'd like.

You guys have given me some ideas, though, so thank you! I'll report back. Still open to ideas, of course...


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## vocatexas (Aug 4, 2021)

Check out Matty's Workshop on You Tube. He recently did a series on his Quorn grinder. I seem to remember him talking about figuring out the order of ops. He's got some other interesting projects on his channel. His channel is relatively new and doesn't have that many subs yet. I really enjoy watching him and Max Grant at the Swan Valley Machine Shop.


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## Rex Walters (Aug 4, 2021)

I still haven't finished mine (had to remake the spindle and OTHER STUFF seems to have put the project on the back burner) but it's very close to finished and I'd have struggled mightily without Hemingway's "Construction notes". I'm sure they'd sell them separately.

The instructions for that part have you first make the pivot bolt and collet on the lathe as well as a separate "pivot arbor" to use as a fixture during construction, leaving the compound at 20 degrees. (Okay, they call it a top slide, but it sounds funny when I write it!)

The pivot stub arbor has a 9/16" long stub threaded to M10 or 3/8" fine pitch, then a 40 degree taper for 1/4" followed by a 1/8" section at 5/8" diameter. The rest is whatever length and diameter you need to hold it in a collet (I used 0.500" diameter). Mill a couple of flats to use with a wrench, err ... spanner, on the end that goes in the collet.

You then layout and rough bore the pivot hole (marked 2 on your casting) in a 4-jaw chuck. They suggest using a scrap of steel (the photo shows a strap clamp) to span across the boss and stop face (1 and 5) to hold things securely in the chuck. Judicial filing by hand let me get everything held securely. Then drill and tap a hole for the pivot stub arbor I mentioned previously.

Next face the boss and index finger until they clean up. Then counterbore the hole to about 0.400" diameter by 0.300" deep. Then cut the 40-degree taper to the same depth. You can also turn the end of the finger to 2" diameter in this setup.

Next, insert and tighten the arbor, then flip it around and hold the arbor in a collet. Face the casting to 1 1/8" and finish the other 40-degree taper.

The next bit is done on the mill with the arbor held in a square collet block and the finger pointing up (you'll want a jack under the boss for support). Drill, bore and ream the spigot bore (1) to size (0.500"). If you are using split cotters, insert a tight-fitting sacrificial arbor in the spigot bore and hold it upright in the collet block, then bore and ream the cotter hole.

Then back to the lathe (I'll post another comment to continue).


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## Rex Walters (Aug 4, 2021)

Good heavens. I haven't touched mine in almost a year and it's SO CLOSE to finished!


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## Rex Walters (Aug 4, 2021)

I bored some friends to death with emails as I proceeded through my build, but I can't find any on that part in particular. I did find a decent image of the final result out of the machine, though.




Anyway, to continue with the Hemingway suggested order-of ops:

You next put a tight-fitting arbor in a collet on the lathe and clamp the part onto it using the split joint or double cotter (whatever you went with). Put the finger toward the tailstock. Use a boring bar to spot face the bottom of the boss to length to a diameter of 7/8". 

Then reverse the casting on the arbor and face the other end of the boss (1" ) and the stop arm (1 1/8") to their correct heights above the pivot bore. Complete the 1/1/2" clearing cut.

Clean up the outside surface of the stop arm, and chamfer the top to 30 degrees and bottom (finger side) to 45 degrees.

Finally, set the compound to 45 degrees and bore the 90-degree taper 1/4" deep.

Leave the compound set and complete the actual spigot (the vertical part that holds the rotating work holding platform and has a taper to match what you put in the gunmetal part). These parts need to be machined accurately and mate well if you want the machine to perform well when you're done.

Back in the mill with a 0.500" arbor clamped in the spigot bore, you can machine the 3/8" wide by 30 degree slot in the tilting bracket.

Do NOT engrave the index marks until the entire machine is assembled and aligned.

Whew! Easier done than written (almost).


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## matthewsx (Aug 5, 2021)

Wore me out just reading it


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## Rex Walters (Aug 5, 2021)

matthewsx said:


> Wore me out just reading it


Send me your email address and I’ll forward you all the blow-by-blows of the build from the past couple of years … ;-)


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## matthewsx (Aug 5, 2021)

You're just over the hill from me, how about you finish it and I bring some bits to sharpen....


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## matthewsx (Aug 5, 2021)

I've got this little one back in Michigan, never really used it yet but I'm sure it'll come in handy some day.









						Hilco Model 2
					

I bought this little universal cutter grinder and can't find anything about it on the interwebs. Motor is a Dumore Type 2GM which I also can't locate.    The machine is pretty simple so I don't think I really need any manuals or the like but it would be nice to know a little history.  Hilco...




					www.hobby-machinist.com
				




John


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## Rex Walters (Aug 5, 2021)

matthewsx said:


> You're just over the hill from me, how about you finish it and I bring some bits to sharpen....


You’re in the queue.


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## Lo-Fi (Aug 5, 2021)

@Rex Walters thanks so much for taking the time! Much appreciated.

I spent a lot of time throwing ideas about myself and came up with this:

File surfaces 1 and 5 flat. Use them to bank on the fixed jaw with the tail hanging over the top. Mill 7 and 4. Drill and ream 2 x 8mm holes 25mm apart. Flip part, bank on previously milled surfaces and mill 3 and 8:




Place 2 pieces of 8mm silver steel in holes, rest on parallels:




This method made it easy to pick up the dowls and edge of the part with an edge finder to get the main bore dead nuts on.
Drill and ream 8mm to be used as alignment in the lathe:





Mill some scrap ali square and drill and ream holes to match the ones in the part:






The bottoms get drilled to clamp the the face plate:




Alingment in the lathe was easy. Leave the bolts just shy of snug, put an 8mm dowl pin the the chuck to pick up the hole started on the mill, spin it by hand to settle everything and snug it down. Indicated within tenths!

Machine in a suprisingly solid setup:




Check fit and adjust the mating part to suit:




Done!




Yes, there is an apprentice mark of shame. I was careless during one of the very first ops! Happily, I have designs on popping it in the rotary table to do some aestetic work on the dial, so that'll disappear anyway. Really looking forward to getting it on the RT!

I should mention that I'll be going the split cotter route, rather the split collar. It suited me to leave the clamp hole 8mm, and will continue to do so until I've done the rotary table work. I can easily pick it back up to open out for the cotters later and the resulting hole need not be crazy precise.

Thanks to everyone for chiming in. There's my solution, for what it's worth! I'm very happy with the result, the fit and aligment are spot on. Onwards!


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## Rex Walters (Aug 5, 2021)

Nice work! Quick, too. I'm sure I took at least two or three days on that part.

I ended up acquiring an old pantograph engraver, mostly to engrave all the dials on the Quorn! The rotary table will come in handy.


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## Rex Walters (Aug 5, 2021)

Oh, one other thing: you're probably well aware but I didn't realize until a few months ago that there is a Quorn-Owners mailing list on groups.io. It's well worth joining.


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## Lo-Fi (Aug 5, 2021)

Sometimes all you need is that one good idea  "What would Joe Pie do?" Kept ringing through my head. "A fixture... That's what he'd do".

Thanks, had no idea about the Quorn group. I'll check that out. I've never tried any engraving before, so that should be an interesting little challenge.

Next up is the circular T slot... That does not look like fun.


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## Rex Walters (Aug 5, 2021)

Lo-Fi said:


> Next up is the circular T slot... That does not look like fun.



The current Hemingway kit no longer sells that part as a casting (doubtless because people hated having to grind a special cutter).

It's now sold as two leaded steel discs. You machine each half separately then just superglue it together.

Just don't do what I did. At one point I decided to lap the back surface to ensure it was flat and pretty. I was pretty jet-lagged at the time, but I had this one circular scratch from the lathe that I just could *NOT* get out. "Geez that must be a deep scratch," I thought.




You don't want to know how long it took me to realize that was the glue-line after fitting the two pieces together.


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## Rex Walters (Aug 5, 2021)

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!


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## Lo-Fi (Aug 6, 2021)

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?


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## Rex Walters (Aug 6, 2021)

Lo-Fi said:


> 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.


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## Lo-Fi (Aug 6, 2021)

Rex Walters said:


> 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!


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## Rex Walters (Aug 6, 2021)

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.


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## Rex Walters (Aug 6, 2021)

Lo-Fi said:


> 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.


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## Lo-Fi (Aug 6, 2021)

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.


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## Rex Walters (Aug 7, 2021)

Lo-Fi said:


> 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?)


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## Rex Walters (Aug 7, 2021)

Lo-Fi said:


> 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?


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## Lo-Fi (Aug 8, 2021)

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!


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## Janderso (Aug 8, 2021)

Rex Walters said:


> 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.


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## Janderso (Aug 8, 2021)

Lo-Fi said:


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


I love the idea of the spring steel to protect the indicator probe.
My Shars diamond wheels have more run out than his.
Lots more work to clean up.
I also like the locking ring! Great idea. I wonder if he re-hardened the Sopko ring?


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