Author Topic: Currin's Travelling Sherline Show  (Read 3875 times)

Offline Flyboy Jim

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Re: Currin's Travelling Sherline Show
« Reply #15 on: July 09, 2017, 03:13:53 PM »
Good morning Hugh,

I followed Chris's lead and made a base plate for my A2Z QCTP. Works great.



As for a portable bandsaw you might think about a Sawzall. I use mine a lot for cutting material.

Good luck on your new adventure. Sounds like fun.

Jim
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Sherline 5400 Mill

Online b.lindsey

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Re: Currin's Travelling Sherline Show
« Reply #16 on: July 10, 2017, 12:39:38 AM »
It's not cnc, but I use a piece of .020" gasket paper between my a2z qctp and the cross slide and it works well, even with some heavier cuts. Has virtually eliminated slipping issues.

Bill

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #17 on: July 16, 2017, 04:31:26 AM »
Well, I looked around the Internet some more about slipping QCTP. With crueby and Jim's info I looked for "Sherline QCTP Plate" and found two interesting links. J. E. Rickenbacker posted about his QCTP Modifications. He used a similar plate but what I found useful was the relief around the center of the QCTP. This puts more pressure toward the outside to resist rotation. "Outlaw" similarly used a plate under his QCTP. He put in a relief but put the relief in the plate, same reasoning.

The reasoning of relieving the center of the QCTP seemed solid. So I chucked up the QCTP in a 4-jaw on the large lathe. Then relieved some 0.008", using a carbide tool, to a diameter that seemed "right".



I also found a post by "John" about using a shim under an A2Z QCTP. He used it just to get the right height. But he mentioned (7th post) that A2Z suggests a piece of copy paper under the QCTP to prevent slipping.

I took Bill's suggestion and used a piece of gasket material under the QCTP. This and the relief seem to help a great deal. Not sure the problem is gone, but moving in the right direction if not arrived. I may key the QCTP to the table as mentioned above, then there is no question. I suspect with CNC there is less need to turn the tool post, and moving it requires all the tools to be re-set (if running a program), a real PIA.

I got the G-code program working well. Was able to cut a tool holder blank in aluminum. Then tried one from 12L14, free machining steel. Here I had some difficulty. The boring went well, but the threading not so much. Boring I was taking a 0.005" depth of cut at around 1000 rpm (Carbide on 3/4" diameter piece), feed rate 4-5 in/min. Similar on the OD, 0.005" depth using HSS. Threading (HSS) I started at 0.005" depth of cut and the program reduced it some as the depth increased, down to some 0.001" at the end. Threading was done at 200 to 300 rpm. To me these seem to be very conservative cuts.

Threading really bogged down the spindle motor, even stalling it a few times. It was also just not happy taking these cuts. I stalled the Z axis stepper motor at least once, not a good thing. The good news is the steppers seem correctly sized for this spindle. Maybe I can't make an internal thread 3/4-16 in steel using the Sherline? It's certainly pushing the limits. I hate to go to less than 0.002" depth of cut, it already takes forever and the tool spring may allow the tool to just rub.

Now the Sherline has a 60W (.08HP) DC motor, continuous 10 oz. in. at 6100 rpm. DC motor should hold torque at low rpm, but lower power with lower rpm. I'm not used to this, my large lathe is 5HP, an increase of 6200%. I have yet to bog it down and conservatively take 0.05" depth of cut, it'll bust tooling though.

For all you Sherline users, how aggressive are you with cuts? In AL? In steel? Any experience threading under power? Any suggestions gratefully accepted.

Thank you all.

Hugh

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #18 on: July 16, 2017, 04:36:32 AM »
As for a portable bandsaw you might think about a Sawzall. I use mine a lot for cutting material.

Jim: Thanks. We have one so the cost would be minimal. I keep thinking of cutting a slice of 12L14 off a round bar for flywheels. I'm not sure I'm up to slicing a piece of 2 1/2" round with a sawzall. Probably doable though.

Thanks.

Hugh

Online Kim

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Re: Currin's Travelling Sherline Show
« Reply #19 on: July 16, 2017, 05:31:30 AM »
Well, I don't have a Sherline, but I do have a Taig lathe (very similar in size and power to the Sherline).  Its been several years since I've used it much but I do remember taking forever to take steel down.  I had to take very small cuts and go slowly.  No more than 10 thousandths per pass, if I remember right.  This was using HSS, not Carbide, but I'm not sure if these little machines have the power, or are rigid enough, to take real advantage Carbide tool.  Just my thinking, though I'm no expert.

Kim

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #20 on: July 21, 2017, 11:47:59 PM »
Kim:

Thanks. That matches my experience though I'm down to .005" depth in steel. The Sherline does cut it but takes awhile.

I have a mix of HSS and carbide. On my large machines I don't push too hard, it is a hobby, and can't tell much difference between HSS and carbide. I run into trouble now and again using too high an RPM with HSS. I don't expect the carbide to be an advantage on the Sherline, it was just the boring bar at hand.

Thanks.

Hugh

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #21 on: July 21, 2017, 11:59:10 PM »
Been thinking a little on cutting a 3/4"-16 internal thread on the Sherline. When I get into the cut the depth of cut is only a few thousands. However, the width of cut is the thread face. For 16TPI that is 0.063" width. For normal thread cutting, feeding in at about 30deg, that is unavoidable. I found a post suggesting an alternative. Here the thread is nibbled away rather than directly feeding in at 30deg. I may try this but it would be a pain to program.

It would also help to put the Sherline in its low speed pulley. I didn't do this and likely should have.

Another alternative is to thread mill them using the cnc mill. This one is feasible.

But for now I decided to use the large lathe and single point the inside. I need to holders to get on to the Stirling build.

Thanks.

Hugh

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #22 on: July 22, 2017, 12:30:03 AM »
SO, I decided to thread the inrernal 3/4-16 Sherline spindle thread on my large lathe. This wasn't too bad but took awhile to build several.

I then drilled holes for the tommy bar and set screw using the Sherline mill set-up. I had a little trouble with the Sherline toolmakers vice slipping. I went to a slightly larger steel toolmakers vice which worked better (or I just reefed on the screw harder). After that it went smoothly. I did notice some flex in the Sherline column. Spot drilling to start a drill I could see some flex and moving outward (away from column) of the spot. Then when drilling I saw the drill shift outward a little as it aligned with the spot. I was using a small spot drill (probably 3/16"). It was better when I switched to a tiny center drill (I think it was a #0) but I could still see the flex and offset. Will take some learning to use these Sherlines.

I used the Sherline lathe to finish the outside of the holders. This went well.

But I used the larger lathe to drill and ream the holders. I don't think I could accommodate the 1/4" or 3/16" reamers in the Sherline due to their length, with drill chuck length. The tail stock is off some 0.005" also. I single pointed a mock up Sherline spindle in the large lathe, and aligned the tail stock to within a few tenths. Then drilled and reamed the holes for end mills.



This worked pretty well. I had three Sherline holders, two 3/8" and one 1/4". I made up another 1/4", two 3/16" and two 1/8". While I was set up for threading I made two additional blanks and three aluminum "face plates". Foolish me, I forgot to make up a blank for an ER-20 collet holder.



Finally, I screwed each onto the Sherline spindle and checked run-out. I put an end mill in each holder and measured off its shank. The results were:

1/8" Holders       0.006"   0.005"    TIR
3/16" Holders     0.003"   0.0045"  TIR
1/4" Holder         0.008"   TIR

I also checked the stock Sherline holders:

1/4" Holder         0.006"  TIR
3/8" Holders       0.0025"  0.0025"  TIR

So, not as good as the stock holders but should be workable.

Now I think I can get back to building some soft top jaws for the three jaw, and a tooling plate or two for milling.

Thanks for coming along. Any comments or suggestions please chime in, I'm flying blind here. :-)

Hugh

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #23 on: July 31, 2017, 01:56:15 AM »
OK. With a few tool holders in hand it was time to use them.

Sherline makes a two piece jaw for its chucks. I've had good luck with soft jaws on my large lathe so wanted to try them on the Sherline. I ordered a set of master jaws and one set of steel top jaws. They make a number of top jaws in steel, aluminum, nylon, brass, etc. The top jaws cost between $54 (steel) and $78 (teflon). They are very proud of their jaws. I thought I could make some give one set of top jaws to measure from.

I cut up some surplus 1/2" aluminum plate using a slitting saw. Squared them up and cut two lengths of about 5". Using a 2" toolmaker's vice tilted at 45deg in the 6" vice I cut 90deg included angle on each length. Each 5" length was cut into 6 pieces and squared to 0.7". All this was done on the knee mill. Could be done on the Sherline but would take a lot longer.

Then on the CNC Sherline mill I cut the bottom to fit the master jaw. This took me some trial and error. I wanted a very good fit so the jaws could be removed/replaces and retain their position. After figuring out the G-code and tooling I cut the base of four sets of aluminum jaws.



Finally, drilled holes with counter sink for 4-40 socket headed cap screws.


These are cut on the lathe to be dead square for general use or for a particular job. A spacer is put in the chuck to hold the jaws tight to the scroll for either holding on the exterior of a part or on the interior. Technically the size cut should be the size of the part to be held. That is their purpose. I've found they are "good" for a range of sizes and I use them instead of the stock hardened jaws, at least on my large lathe. They don't mar parts as bad. We'll see if they are as useful at the Sherline size.

Here is a picture of the new aluminum jaws along with the Sherline steel jaws.


The stock jaws in the front and new aluminum jaws in the back.

I have a couple of tooling plates in the works. Those and a tap guide and I think I'm ready to get back to the Stirling.

Thanks.

Hugh

Online Kim

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Re: Currin's Travelling Sherline Show
« Reply #24 on: July 31, 2017, 05:34:58 AM »
Yeah, the Sherline accessories are always a little spendy. That's one of the reasons I went with Taig - the cost of the accessories!  In this case, the softjaw set for the Taig 3-jaw costs $11 or so. I've got several sets.  But they don't offer teflon, nylon, or Brass.

You're getting all kitted out here Hugh!  And great work saving a boatload of money by making your own jaws!

Kim

Offline gerritv

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Re: Currin's Travelling Sherline Show
« Reply #25 on: July 31, 2017, 11:38:11 AM »
Excellent tool making, one of the many joys of the hobby!

Have you seen Luiz Ally's YouTube videos? His shop is loaded with Sherline CNC stuff.
He has an excellent couple of videos on making hss cutting tools from round blanks. They cut steel very nicely. I made a version for my AXA tool holders on 10x22 lathe.

Programming is like a Hit-n-Miss engine

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #26 on: July 31, 2017, 04:52:48 PM »
Kim: Yes, the Sherline equipment is expensive but very well made. The milling tool holders I made above are some $30 each from Sherline. They are better than I can make, and a good deal for one or two. But for 5-6 it's pushing $200, no longer trivial. But then at $10/hr mine are probably some $500 each. But all that time is learning to use the Sherlines, so well worth it and enjoyable.

gerritv: I've seen a few of his videos. The subtitles are distracting but he makes some very nice tooling. Do you remember which one shows making HSS tools?

Thanks for following along and for the comments.

Hugh

Offline gerritv

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Re: Currin's Travelling Sherline Show
« Reply #27 on: July 31, 2017, 06:15:37 PM »
Certainly:
Micro Tool holders ,Part 1 , Part 2, Part 3
Making micro cutting tools A 4 part series.

end mill holders

I think he also has a newer tool holder design that fits directly on a 0XA tool post.

« Last Edit: July 31, 2017, 06:30:21 PM by gerritv »
Programming is like a Hit-n-Miss engine

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #28 on: August 01, 2017, 04:50:15 AM »
gerritv:

Thanks. He certainly has built some nice tooling for his Sherlines. I really like his low profile vice, I think I need to build one of those. I'll have to find some more time to review more of his videos.

Thanks.

Hugh

Offline Hugh Currin

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Re: Currin's Travelling Sherline Show
« Reply #29 on: August 01, 2017, 05:03:54 AM »
Here is the next piece to the puzzle. I made a spring loaded tap guide for the mill. I started with a length of 3/8" 0.028 wall tubing and a spring that seemed right from the local home supply store. I pressed a 0.7" length of brass into one end of the tube and reamed a 1/4" hole though. The plunger was machined from drill rod (silver steel) because it was handy. The parts are below:


The cap was supposed to press on to capture the spring. I had to resort to lock-tight though as it was a little loose.


It has about 1" of travel. To use it is placed in a tool holder and put on the spindle. A tap wrench is held between the hole to be tapped and the guide. The spring puts slight pressure on the tap but mainly keeps the tap straight to the hole.


I built and use a larger (3/4") guide on the knee mill and it works very well. I hope this will work as well.

Thanks.

Hugh