Making tools with my tools

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Jawn
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Location: Canton, GA

Making tools with my tools

Post by Jawn »

First (successful) attempt at a lathe project: drill arbor

I say successful, but there's things I may do differently in a second go-round (turning final shank diameter with chuck installed to correct for runout... bad idea or no?)

I had an old Jacobs 3/8" chuck laying around... now that I have all this machinery, why not make use of it? Turned a 1/2" straight shank to fit a mill collet, then turned and threaded the other end to match the 3/8"-24tpi of the chuck. I think I'm getting the hang of this.
drillarbor-1.jpg
drillarbor-2.jpg
Last edited by Jawn on Thu Nov 06, 2014 10:30 pm, edited 1 time in total.
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wsippola
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Re: First (successful) attempt at a lathe project: drill arb

Post by wsippola »

Nice job on the arbor Jawn!

I don't think turning the final diameter while the arbor is mounted in the chuck would help much. I suspect if you did that, the runout would still vary with the diameter being chucked.

If your collet was accurate, the way you did it should work just fine. Between centers might be slightly better, but I doubt it would matter in any practical application unless using one of those really high precision chucks.

Wayne
Patio
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Re: First (successful) attempt at a lathe project: drill arb

Post by Patio »

Nice job on the arbor. It looks good from here. Have you tested the run out? It may be better than you think.
You did not say how you made it. 3 jaw, 4 jaw or collets?
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Jawn
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Re: First (successful) attempt at a lathe project: drill arb

Post by Jawn »

Patio wrote:Nice job on the arbor. It looks good from here. Have you tested the run out? It may be better than you think.
You did not say how you made it. 3 jaw, 4 jaw or collets?
3-jaw. My 4-jaw has issues, and I don't yet have a collet setup. I do have about .0025" measured runout with a 1/2" bar in the 3-jaw chuck, but I ignored that since this was more an exercise than anything. I'll put the new arbor/chuck in the mill and measure it next time I'm downstairs.

I say I don't have a collet setup, but I did acquire a body casting for a MLA loop collet chuck... to be built when I have the confidence in my abilities to try it.

http://www.statecollegecentral.com/meta ... MLA21.html

I have the body casting only, so I'll pick up a backplate and some stock for the nut as well as other hardware (bearings, screws, etc). Guess I'll have to order the drawings too.

Another upcoming project will be a small fly cutter for the mill. I have some 1" stock... was thinking turn one end down to 1/2" and angle/slot the other end for a 1/4" bit.
Jawn
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Re: First (successful) attempt at a lathe project: drill arb

Post by Jawn »

Jawn wrote:
Patio wrote:Nice job on the arbor. It looks good from here. Have you tested the run out? It may be better than you think.
You did not say how you made it. 3 jaw, 4 jaw or collets?
I'll put the new arbor/chuck in the mill and measure it next time I'm downstairs.
Just tried it out...

placed chuck/arbor in R8 collet on mill, placed 3/8" drill blank in chuck. Measured .006" near chuck, and .008"-.009" 3-4 inches down. Not as bad as I thought (the 5/8" chuck on my drill press is more like .015" near the chuck).
Patio
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Re: First (successful) attempt at a lathe project: drill arb

Post by Patio »

Jawn, chasing run out can be interesting some times. If it was me, I would check the run out in the spindle first, by putting a piece of round stock, that is know to be round and straight, in a collet. That will tell you how much of the run out you have is in the machine, and how much is in the new arbor.

Does you 3 jaw have a set of 2 piece jaws? If so, you can make a set of soft jaws, that will correct all the run out you may have in your lathe.

I will be watching to see what all you make with your new machines. :)
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Jawn
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Re: First (successful) attempt at a lathe project: drill arb

Post by Jawn »

Patio wrote:Jawn, chasing run out can be interesting some times. If it was me, I would check the run out in the spindle first, by putting a piece of round stock, that is know to be round and straight, in a collet. That will tell you how much of the run out you have is in the machine, and how much is in the new arbor.
I checked it, IIRC it was around .001"... but I could be mistaken. I'll check again when I get a chance.
Patio wrote:Does you 3 jaw have a set of 2 piece jaws? If so, you can make a set of soft jaws, that will correct all the run out you may have in your lathe.
Nope, frayed knot.
Patio wrote:I will be watching to see what all you make with your new machines. :)
Already onto the next... making a small fly cutter now!
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Re: First (successful) attempt at a lathe project: drill arb

Post by Patio »

A suggestion on the fly cutter, make the shank 3/4", if you have a collet for it, it will be more rigid.
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Jawn
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Re: First (successful) attempt at a lathe project: drill arb

Post by Jawn »

I accidentally went a hair under 3/4... about .748" so far. I wonder if that'll work ok, or if I should cut it down to 5/8"? I haven't tried to clamp it in a collet yet, but just the bare collet is an easy slip fit right now.
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Harold_V
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Re: First (successful) attempt at a lathe project: drill arb

Post by Harold_V »

Jawn wrote:I accidentally went a hair under 3/4... about .748" so far. I wonder if that'll work ok, or if I should cut it down to 5/8"? I haven't tried to clamp it in a collet yet, but just the bare collet is an easy slip fit right now.
While the amount of error is small, collets that are not split at both ends work very best when you use them at the nominal diameter. Anything larger causes the collet to grip at the rear of the hole, and smaller at the front of the hole, although if you apply enough pressure on the draw bar, it may deform the collet enough to grip full length. In either case, the slight amount of movement that is possible can be troublesome, especially for interrupted cuts, which are often the case with a fly cutter.

My personal choice would be to make another fly cutter. If you try to standardized on one size, you can switch from drill chuck to fly cutter to end mill (assuming the same size shank as the chuck and fly cutter) without switching collets. That's a very nice feature if you operate machines for gain, or if you hope to make your limited shop time more productive.

Some folks may not care about that. For them, my advice would be to make the shank the next smaller size for which I had a collet. Considering my R8 collets are sized in 1/16" increments, I'd shoot for an 11/16" shank if I didn't want to make a new one. Keep as much shank diameter as you can, for the sake of rigidity. Doesn't matter all that much when fly cutting aluminum, but, for steel, you need all of the advantages you can possibly gather.

Harold
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Patio
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Re: First (successful) attempt at a lathe project: drill arb

Post by Patio »

Jawn, the quest for precision can either be fun or frustrating, depending on how far you try to take it. I always try to get as close to what I am shooting for, every time. Even when not necessary. The theory is, that I will be able to do it when it is required. This month makes it four years since I took up machine work. I now rough to get with in .010" to .015" of the finish diameter. Then I take a cut that will supposedly take a third of that, measure and take the next third, by then I will know what my final cut should be to get to the finished diameter. If I have any doubts, I will shoot for .001" over sized and polish, with an emery cloth, to finished size. The reason for taking a third each time is, each cut will load the tool the same, so the cuts should become predictable, allowing you to finish on your mark. It doesn't always work out that way, but that is why I consider it all practice. :) Once you try to work under .0005" you will need a grinder, and things can get interesting.
I have been listening to Harold's advise from the beginning. I have not been steered wrong yet. :)
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Patio
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Re: First (successful) attempt at a lathe project: drill arb

Post by Patio »

Jawn wrote:I accidentally went a hair under 3/4... about .748" so far. I wonder if that'll work ok, or if I should cut it down to 5/8"? I haven't tried to clamp it in a collet yet, but just the bare collet is an easy slip fit right now.
If you have not finished the fly cutter, you may want to turn the shaft down to the next size, and finish the whole thing, before you make the next one, with a 3/4" shaft. You will encounter all the problems with the first one, so the second one should come out much better. Most things I make, I could have done better on the second one. I have finished making parts that I knew would be scrap, just to figure out the problems before making a finished piece.
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