Newbie getting in over my head?

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Harold_V
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Re: Newbie getting in over my head?

Post by Harold_V »

What might help make up your mind would be to do the math on the bolt circle to see what the overall diameter over the counterbores would be. If they don't break out on the perimeter, the smaller one might serve perfectly well. If not, I suspect that they are made of either gray iron, or "semi-steel", both of which are easily machined, so it then gets down to a matter of economics. Cutting down an 8" plate shouldn't be all that difficult, especially if you can use a grade 2 carbide (such as GE's 883). On that diameter, assuming you have the power, it would do a great job.

I would be more inclined to spin polish the chuck body than to bead blast. By using a large flat stone, you can achieve decent results and restore the chuck to what would be its original appearance without rounding edges. That said, so long as the body is blasted while the chuck is not assembled, no big deal. All depends on what you hope to have it look like.

I don't know the level of your ability, so please accept the following in the spirit in which it is offered.

Measuring the diameter of the short depth of the counterbore that accepts the spigot you must machine on the backing plate would be difficult at best, and calipers are NOT to be trusted to yield an accurate reading. If you intend to use a caliper, do so ONLY to get close to size (no closer than ten thou). Do NOT rely on the caliper for the desired fit. That's almost a guarantee of not hitting size.

I'd like to caution you that the spigot that locates the backing plate in the chuck body is critical. It should be dead concentric with the spindle and a snug fit in the chuck. If it is a poor fit, you risk having the chuck body move about on the spigot and it won't register the chuck as it should.

Before mounting the new plate, run the spindle at high speed and lay a flat stone on each of the critical faces to ensure that there are no dings that will alter the desired relationship between the plate and spindle. Anything that stands proud will be readily disclosed and removed. Also, check the plate for any dings BEFORE mounting for machining. If any are found, be sure they are FULLY removed so they don't alter the desired running condition.

Regardless of the amount of time it takes to fit the plate, once you are close to size, take one thou passes and check for fit with each pass by taking a shallow cut and checking the fit before completing the cut. If the chuck doesn't slip on, take the cut to depth and repeat. Do NOT change the dial setting until each pass is complete, otherwise the resulting size may not be reflected in the finish pass due to cutting pressure variations. With a sharp tool, a thou cut in this material isn't difficult. Remember, what work you do now will be reflected in the performance of the chuck until the day you no longer operate the machine. It's worth taking the time to ensure the proper outcome.

H
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nessism
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Re: Newbie getting in over my head?

Post by nessism »

I understand how to machine the backplate.

I tried to clean up the surface finish, but the pitting is too deep. Oh, well. At least it's functional.
nessism
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Re: Newbie getting in over my head?

Post by nessism »

Still working this project...

Found a suitable backplate for the Kitagawa, and machined it to fit. All good, except the chuck shows about .005" of runout when indicating a ground bar. If I remove the 2 piece jaws, and clamp the bar in the scroll jaws, the runout drops to about .002". 3 jaw chucks are for first operation cuts, right, so a little runout will be eliminated after the first cut? Anyway, I'm not worrying about it for now.

Bigger deal, I'm going to make a stand for the machine. The stock stand is too tall, and made from sheetmetal. I'm going to get some 2" square tubing and have a go at welding together something nicer. I'd love to find a nice, reasonably priced, toolbox to stick into the middle of the stand. Gotta dig on that...
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Bill Shields
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Re: Newbie getting in over my head?

Post by Bill Shields »

What is the runout in the OD of the chuck?
Too many things going on to bother listing them.
nessism
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Re: Newbie getting in over my head?

Post by nessism »

I've been working on making a stand...and learning how to weld. Burned me a pile of rods while practicing, and reached the point where I'm confident in strength, but my welds won't win a beauty contest.

The support legs have nuts welded inside for adjustable feet.

This stand is tons more sturdy than the sheet metal original, and it's shorter. It's 4.5" wider, and a little longer too. This weekend is clean up and painting time.

I still haven't sorted the chuck issues. I've bought two different brand-new chucks, and neither seats properly on the lathes spindle. That will be the first project once the lathe is on its new stand. Got a DRO, and need to make a back splash panel too.

Good fun...

Image20230805_090702[1] by nessism, on Flickr
Last edited by nessism on Sat Aug 12, 2023 5:17 pm, edited 1 time in total.
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NP317
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Re: Newbie getting in over my head?

Post by NP317 »

Progress.
Looks like you need more heat (amperage) for your welds.
My distant guess.
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nessism
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Re: Newbie getting in over my head?

Post by nessism »

NP317 wrote: Fri Aug 11, 2023 10:58 pm Progress.
Looks like you need more heat (amperage) for your welds.
My distant guess.
RussN
What I need, is more skill! :mrgreen:

My big fear was burn-through, because I did just that numerous times while practicing. And as you know, high amps = increased burn-through risk.
Good news, I learned to fill in a burn-through, and only had a couple of minor events on the actual stand.

On the end supports, where the highest stress will be, a high-skill welder friend helped me. Again, I'm confident in the strength, which is the main thing...
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NP317
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Re: Newbie getting in over my head?

Post by NP317 »

👍🏼
RussN
David2011
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Re: Newbie getting in over my head?

Post by David2011 »

Just read through the whole discussion. Any updates?
nessism
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Re: Newbie getting in over my head?

Post by nessism »

David2011 wrote: Mon Oct 16, 2023 6:38 pm Just read through the whole discussion. Any updates?
Thanks for your interest, David... And sorry to all you guys hanging on my next move. :roll:

The stand is done. Yeah! Even got shelves made for when the machine is properly placed.

Also got the DRO installed. I'm using a TouchDRO unit and Amazon tablet. Glass Sino scale for the Z axis, and a smallish magnetic Ditron scale for the cross slide, for space reasons.

My latest project is installing a back splash panel. Instead of making one from scratch, I bought a unit from Grizzly that is close, but just needs some minor tweaking. I've been delayed due to medical issues, but the light is bright on the other side of the tunnel in that regard, so I'm hoping to be done soon...

Image20230902_125850 by nessism, on Flickr

Image20231021_125331 by nessism, on Flickr

Image20231021_150403 by nessism, on Flickr
David2011
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Re: Newbie getting in over my head?

Post by David2011 »

Congrats! It looks great.
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Bill Shields
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Re: Newbie getting in over my head?

Post by Bill Shields »

There you go 🙂
Too many things going on to bother listing them.
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