Welded construction for surface grinder arbor?

[Flynth]

Wow $340 for a wheel hub (similar to what I was quoted).

Thanks, I'll be making a few for my surface grinder as well. I have a Delta - Milwaukee tool /surface grinder. The hubs are not standard, and are very expensive. Sopko lists them, but they are not in stock. I bought a rod of 3 inch or 3.5 inch 1144. I might try the 2 piece method and do the weights as one piece rather than split. And when pushing the arbor into the backing, capture them. Seems like it would be the way to go. And I would not pin them together. Rather I would create a chamfer on the wheel side of the backing plate, and just silver solder it. That's all that would be needed.
I think the multi piece hub is a better way to go, so if I mess up a part, I am not out the entire large piece. And that way I can make more. I have a bunch of thin wheels, so I can make short and also cup and diamond holders.
Your idea has been quite helpful thanks.

Would that be a 3 piece (plus weights) method? An arbor, then the two part backing plate to capture the weights as you mentioned you prefer them captive.

I have had a piece of old pin from a large digger of some sort that was 93mm in diameter (almost 4 in) and long enough for one wheel hub so I started making it as one piece.

Currently I'm done with the wheel side (and a washer) and I'm in finishing stages of doing the taper from the back. I measured it multiple times and it appears the taper is exactly 1:10 (5.7 degrees or so). I also have a wheel balancing arbor with the same taper.

My plan was to rough the taper on my large lathe The part held in a 3 jaw chuck, had to be reversed and I measured about 1.5 thou of positioning error after reversing the part (this is after a lot of fiddling, rotating the part, adding very thin shims etc). The plan was to finish the taper in my Chinese mini lathe after putting it into a 4 jaw chuck. My Chinese mini lathe has been holding really good tolerances (well better than 1 thou) as long as there is no chatter.

So I got that taper within half a mm (20 thou) and I started thinking before removing it from the large lathe that I even got some chatter in my big lathe. It is very unlikely I'm going to be able to clean it up well with a skinny and long boring bar, plus the little 4 jaw will hold it by the thread, or a washer by a quarter of an inch. It didn't sound like a good plan at all. Also I thought, slight error in concentricity between the wheel and the taper will be taken out by the wheel dress. So I decided to finish it on a big lathe. I'm not sure how usable that wheel hub will be for diamond wheels. If not very, I can use it with normal stones only.

I got it within 5 thou and I had to finish for the day. Now I wonder, should I take this remaining 5 thou with the brazed carbide boring bar I've been using all the way? It has worked ok so far, surface finish wise - lines are visible, but can't be felt with a finger. Or should I try to sand it down with sandpaper for the last thou?

The test arbor locks in properly even without sanding and there's always a risk of ending up with an egg shaped bore. What's your opinion?

Here is how it looked:
The part

Test arbor (too small, but still fits into the front quarter inch of the taper).

Arbor in for measurement.


This balancing arbor is for a much smaller grinder, but the taper matches enough to be of use.

I'm still to make the face grooves and the weights. I watched Joe Pie video on YouTube about face groove/trepan tool grinding. When he was describing types of what he calls trepans (face grooves) he mentioned "and the last type is a dovetail trepan, it's always a nightmare". Oh boy. It would be a shame to scrap it at last feature. If anyone knows of any videos showing those being cut with self ground tools I would very much like to see it.

 

[woodchucker]

No the Sopko is without weights, just plain if I remember correctly.

My preference would be to internal grind the bore the final distance. That way I get a nice super smooth bore/taper.

Here's a thought on finishing the face of the hubs that mate with the wheel face. You want that as true as possible also. I would lap a grinding stone, maybe an 8x3 flat on a lapping plate. I would take the stone a backing plate and a piece of cardboard, clamp the 3 in a vise on your magnetic chuck, and true it square, then run the hub and move it across the stone while traversing the carriage back and forth. I would use coolant.

That's just my opinion.. Just an idea, don't know if it's good or bad.

 

[Flynth]

No the Sopko is without weights, just plain if I remember correctly.

My preference would be to internal grind the bore the final distance. That way I get a nice super smooth bore/taper.

Here's a thought on finishing the face of the hubs that mate with the wheel face. You want that as true as possible also. I would lap a grinding stone, maybe an 8x3 flat on a lapping plate. I would take the stone a backing plate and a piece of cardboard, clamp the 3 in a vise on your magnetic chuck, and true it square, then run the hub and move it across the stone while traversing the carriage back and forth. I would use coolant.

That's just my opinion.. Just an idea, don't know if it's good or bad.

That sure is an idea that could work, but I would worry about the stone loading. One would have to leave a little excess material to allow for grinding. I haven't thought about it on my first DIY hub. I might use it for the next. Alternatively I might make a better arbor to mount the wheel hub in a spin fixture and cylindrical grind it properly while holding it by the taper. That would be best.

I'm pretty much done with the main piece of my first diy hub. Ideally I would like to have at least 3 so there is at least 1 to go. I was worried flipping the part in my 3 jaw would ruin the concentricity between the wheel mating cylinder and the taper, but measuring both the original wheel hub and my new one I can't detect a difference. However, to achieve this I did spend an hour adding thin shims and rotating the part etc in the 3 jaw. Wheel hub no 3 will definitely be cylindrical ground to size.

The dovetail trepan (or face grooves) weren't that difficult to cut. I was really worried about breaking tools and scraping parts, but going slow (100rpm and feeding at 0.02 per rev - about a thou per rev - manually) worked pretty well. I ground 3 hss tools. 1 a straight face grooving tool, one right and one left 15 degree dovetail face groove. I first made the face groove with rectangle cross section, then I made the dovetail features by angling the compound/ top slide.

The finish is not that great, but it'll do. Buying a mini tool cutter grinder has been one of the best tool buying decisions in my shop. Here are 2 of the tools:


Grooved part, before dovetails

Dovetail trepan setup.

Afterwards

Original weights fit fine

And the new wheel hub next to the old

I have no idea what are those two holes (one of which is visible on the original hub) are for.

If anyone has an idea please let me know.

 

[woodchucker]

One more thing, just throwing out ideas.
if you have a tool post grinder, you could mount it on your surface grinder and mount your hub on the surface grinders spindle and do the finish grinding on the surface grinder. As a matter of fact you can probably also do turning on the surface grinders spindle, albeit very , very lightly

 

[jwmelvin]

Those two holes look like they are for a face spanner to hold the hub while tightening.

Looking great; thanks for sharing your process.

 

[Flynth]

One more thing, just throwing out ideas.
if you have a tool post grinder, you could mount it on your surface grinder and mount your hub on the surface grinders spindle and do the finish grinding on the surface grinder. As a matter of fact you can probably also do turning on the surface grinders spindle, albeit very , very lightly

Unfortunately I don't have a proper tool post grinder, but I have a spin-indexer with a tailstock. So for the next hub I plan making an arbor to be able to mount the hub in the spin fixture. Then I can cylindrical-grind both the diameter and the face. Also I could do it the opposite way. Mount a grinding stone in the spin fixture and put the wheel hub on the spindle nose. This would have an added advantage of it removing any spindle taper runout.

Either way I'll need another "balancing" arbor. The one I have, being smaller, it holds on the front 8mm (a bit over quarter inch) only. That's fine for balancing, but I wouldn't trust it for grinding. Now that I think about it, I definitely need a retaining screw in that arbor too to use it for grinding.

Those two holes look like they are for a face spanner to hold the hub while tightening.

Looking great; thanks for sharing your process.

Yes, that's right. Thank you. It didn't cross my mind as I always hold the wheel in hand during tightening. It looked like a later modification to me, but clearly it isn't so I'll have to drill those holes too.

I don't understand why the manufacturer didn't include a drawing of the wheel hub in the manual. There are 30 drawings including an optical dresser, a foundation drawing, a chapter how to mount it on a sea going vessel, but no original wheel arbor drawing...

Also, perhaps someone has an idea what may be the purpose of these grooves:


There is a depression around the spindle taper so when the wheel hub sits on it, it's partially below the surface, in a hole very slightly larger than its diameter. Those grooves are in the hole. The only thing I can think of is they're meant to allow grit and dust to have some place to go rather than reaching the spindle. Does that sound right? Do other grinders have this feature? If so, I may need to add them.

 

[woodchucker]

I think they wanted you to buy hubs, so no drawings.
I wonder if those grooves around the flange might have been worn in by trying to grind too close to a vertical piece on the part they were grinding, or on a plate that was used to support the piece that was grinding. It might have been that the wheel wore and rather than replace the wheel, they didn't notice or just kept going (after noticing).

 

[Flynth]

I think they wanted you to buy hubs, so no drawings.
I wonder if those grooves around the flange might have been worn in by trying to grind too close to a vertical piece on the part they were grinding, or on a plate that was used to support the piece that was grinding. It might have been that the wheel wore and rather than replace the wheel, they didn't notice or just kept going (after noticing).

That couldn't happen, because those grooves are inaccessible when the wheel is mounted. It's difficult to explain this arrangement, but I'll try.

This is a profile drawing

As you can hopefully see those grooves sit below the surface. So they are inaccessible. Also they look very "purpose made". They have exact same width and depth.

 

[woodchucker]

perhaps they are there for holding purposes when mounting a new wheel on the adaptor. Maybe there was a jig to grip those while it was off the machine so you could tighten the nut (although you never need to put a lot of force on the nut) or maybe to grip to loosen it.

I know you want a real answer, I don't have one, just throwing ideas out there. And from the lack of response, it seems like no one has an answer, or they haven't viewed the thread.

 

[Flynth]

perhaps they are there for holding purposes when mounting a new wheel on the adaptor. Maybe there was a jig to grip those while it was off the machine so you could tighten the nut (although you never need to put a lot of force on the nut) or maybe to grip to loosen it.

I know you want a real answer, I don't have one, just throwing ideas out there. And from the lack of response, it seems like no one has an answer, or they haven't viewed the thread.

I have one and I can't tell either perhaps it's decorative?

One more thing to add, if anyone is making those face groove dovetails and stuff that fits inside definitely take into account extra clearance...

Unfortunately I haven't and now my weights don't fit. However I should be able to open the dovetails slightly. I still have quite a bit of metal there. I tried to make one of the weights less tall, but the angle is so shallow I would need to remove too much. (I'll have to put some braze back on its bottom to make it weight same as all the others as I ground over a mm off during testing).

The process of making those weight I came up with was to make the outside a slight interference fit on the inside. Then press it on, drill and tap like this. If this doesn't make much sense perhaps photos will.


Now, I couldn't measure the bottom of the original "circular dovetails" so I measured the weights instead, but as I said I didn't account for any clearance...

Thankfully I have a good 3 jaw that is very repeatable so I can just cut a bit more on the wheel hub.