Machining Setup's with Few Comments

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Thu Jun 15, 2017 10:31 pm

The final photos showing how a threaded blank was turned to length and the slotting of the set screws with a fine screw slotting saw.

The finished set screws have to be hardened and slightly tempered or given a good case hardening to ensure their long life.
Attachments
279 Trimming a Set Screw to Length Utilizing a Split Nut.jpg
280 Slotting a Set Screw with a Screw Slotting Saw.jpg
282 The Finished Set Screws (long and short).jpg

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Thu Jul 20, 2017 8:47 pm

More headaches.

I have a Quorn T&C grinder but to make it useful, it has to have dozens of accessories which are just as much work and trouble as making the basic machine itself.

Of the endless accessories needed are the many types of arbors to fit the work head bore which is 1.000" on the drawings but on my machine the original builder fine bored the work head out to 1.0025" which now makes every work head arbor a "special".

One of the arbors is a #2 MT socket (bored out at the other end to accept a #2 MT collet drawbar) which will allow the use of #2 Morse taper collets up to 1/2". Commercial blind MT sockets (both hardened and ground) are available at machine tool suppliers for use in a turret lathe at reasonable cost.

I was never going to be able to successfully produce a #1 or #2 MT socket to the accuracy of a commercially made accessory so I bought 2 of them having a 1.250" OD with the idea of turning the body down between centers in my lathe to the needed 1.0025" diameter.

It was a h-ll job and I never thought the problems would end but finally I managed to turn the commercial #2 MT socket down the the required OD straight and on size to 0.000" -+ 0.0003" finishing it with a dead smooth file and some 320 grit wet and dry paper. The only reason I could do it was because the #2 MT socket was from an offshore supplier and it turned out not to be totally hardened throughout.

Do I really think that the socket's internal #2 MT has been ground dead true - no, not really but then there is not much choice in this case. I could go on about all of the details on how to make your lathe turn dead parallel between centers and how razor sharp the cutting tools need to be but I won't.

Finally, never again - I am not even going to try with the commercial #1 MT solid socket.
Attachments
284 Commercial Morse Taper #1 and #2 Solid Sockets for the Quorn T&C Grinder.jpg
285 Turning the Body of the #2 Morse Taper Solid Socket to Fit the Quorn Workhead.jpg
287 Turned Body of the #2 Morse Taper Solid Socket with the Unturned Body of the #1 MT Solid Socket.jpg

spro
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Re: Machining Setup's with Few Comments

Post by spro » Fri Jul 21, 2017 12:27 am

I see a lot of work. I see beautiful finishes. I see a South Bend and the toolpost and tool holder set for maximum rigidity. I don't have to tell you this is good stuff. but did anyway :)

spro
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Re: Machining Setup's with Few Comments

Post by spro » Fri Jul 21, 2017 2:24 am

There are questions and other things but getting late for here.

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Fri Jul 21, 2017 9:01 am

Hi spro,

It didn't start out this way. I could have benefitted from having a much more rigid lathe. To cut through the outer heavy duty case hardened surface was a nightmare. Even cemented carbide (the C5 grade for steel) lost its cutting edge quickly as perhaps the lathe was vibrating and microchipping the carbide cutting edge. Anyway, HSS finally did the job. I use large positive rake angles with a small round nose tip exactly as shown on the SB HSS tooling sheet as they know their lathes better than anyone else. Large positive rake angles weaken the cutting tool and require one to frequently re sharpen the cutting bit (the price you pay) but it did produce the best surface finish with the 9" SB bench lathe. For the final "scratch" finishing cuts, the HSS lathe bit was touched with a honing stone (which is also recommended in the SB tooling sheet).

My bench lathe is mounted on a heavy wooden bench which is one of the worst types of mounting one can have (it is a custom made beautiful piece of industrial "furniture" and I really like it but ...) because no matter how heavy the wood is, it swells and shrinks with temperature and humidity changes. For 98% of the work we do, it doesn't matter if the lathe is mounted properly (i.e. any twist in the lathe bed is taken out by levelling the lathe bed and shimming) but for this type of work it does so I borrowed a friends master precision level to check any lathe bed twist. That is a story in itself as if one turns on the lathe bench light or stands next to the lathe bench, the bubble moves. I used a couple of orphan (same size) gage blocks to set the level on on the flat sections of the front and back ways of the bed and a large vee block set square across the bed ways (and clamped) to bring the level into the exact same position when it is reversed also remembering to have the exact same overhang of the level at each end.

Then the fun began as I could not get consistent readings (either short term - after 10 minutes of sitting still or long term - sitting overnight) until I discovered that the level itself needed adjusting ever so slightly as per the Starrett instructions which came with the level.

Not only are the endless lathe checks needed, money flows like water as one has to buy the sockets, the stub arbors (of dubious quality) to fit the internal Morse tapers so that now one has two centers to work with, I also bought an American made high quality #2 MT finishing reamer, if needed, to remove any micro scratches and scores in the lathe's tailstock barrel as well as a #2 Morse parallel test bar to test the lathe's tailstock alignment with the headstock of the lathe (on the 9" SB lathe, the headstock is dowel pinned to the lathe bed so its alignment is factory set) and a between centers parallel test bar made many years previously.

Best practice also dictates that the lathe centers should be ground in place (and marked as to their position in the headstock and the tailstock tapers) which necessitates access to a small toolpost grinder- it just goes on and on.

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BadDog
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Re: Machining Setup's with Few Comments

Post by BadDog » Sat Jul 22, 2017 12:40 am

It's been a while, but for hard steel I believe C6 is the preferred choice. With a faster and more rigid/powerful lathe I would suggest Cermet. Glenn first got my attention on those a few years ago, but for very light/fine cuts and wonderful finish in hard steel, they can't be beat. And modern coated carbide inserts would do the heavy lifting. But neither on a light lathe. So I think a finely honed C6 might have been your best bet. Or maybe Stellite or Tantung would be the ultimate option for your lathe.
Russ
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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Mon Jul 24, 2017 8:16 pm

Finished #2 MT socket with drawbar and collet.
Attachments
288 Finished #2 MT Socket with Drawbar and Collet.jpg

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Sat Jul 29, 2017 9:17 pm

More fun in the shop this time with what I call "precision" split bushings - a precision split bushing being something between a regular split bushing and a collet.

Recently, I bought a very cheap (one of the best brand name) but very dull 1/4" dia. counterbore (new brand name counterbores are not cheap to buy!). I was all set to sharpen it in the Quorn utilizing the new cut down #2 MT solid sleeve just completed when I realized that the shank of the counterbore was not made to any fractional inch collet size being 0.228" in dia.

As this situation has come up before, my solution has been to drill and precision bore a split bushing- the ID of the bushing being a very close slide fit to the OD shank size of the counterbore and the OD of the bushing to to a fractional inch collet size exactly (in this case 1/2"). To make it a "precision" split bushing, the bushing blank is slit in 3 places 120 degrees apart. One of the slits is right through to the ID of the bushing while the remaining two slits are slit to a depth leaving about a 1/32" thick wall. This allows the collet to close on the bushing which in turn closes on the shank of the tool. A single through slit in the bushing still leaves it too resistant to closing on the work when the collet closes on the bushing.

To do the machining, a close fitting 5/16" dia. arbor was first turned in the lathe, the arbor being held in a collet. The arbor end was drilled and tapped for a cap screw and washer and the machined section of the arbor is made slightly shorter than the split bushing blank length so that the cap screw end locks the bushing blank in place when it is tightened up for the slitting operation which follows.

For the slitting operation itself I have a B&S type semi universal dividing head and new high quality 3 jaw chuck which holds the arbor but one could use a spin index with a collet also. Just run the screw slotting saw slowly and use lots of cutting oil for the slitting operation.

I may still have to make up a second hollow draw in bar on the cut down #2 MT socket sleeve to accommodate these long shank tools. One's work is never done.
Attachments
289 Setup Employing a Screw Slotting Saw and Arbor to Produce a Custom Precision Split Bushing.jpg
290 Some Examples of the Custom Split Bushings Made.jpg
291 Closeup of the Precision Split Bushing Held in a #2 Morse Taper Collet.jpg
292 The Arbor Used to Hold the Precision Split Bushing in the Three Jaw Chuck.jpg

ncollar
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Re: Machining Setup's with Few Comments

Post by ncollar » Sun Jul 30, 2017 2:25 pm

very nice work Carrdo, love seeing pictures because I know what it takes to get a part there. keep it coming
Nelson

spro
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Re: Machining Setup's with Few Comments

Post by spro » Tue Aug 01, 2017 11:27 pm

Yes fine work. I comes back to me that the Universal Engineering collets of ZZ size ( up to 1") were built that way. They are DA collets so they compress at the face. One of the kit broke because it was compressed to a smaller diameter. It was the 1" and couldn't handle that flex. It broke at the web and actually still worked if the correct diameter of shaft was used.
They are DA/ dual angle so compress the inner and outer.

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Mon Dec 04, 2017 12:29 pm

Another setup for the precision slicing of blue tempered spring steel in my 7" Atlas bench shaper.

I have to say a few words about this.

Firstly, everything has to be very, very rigid and secure as the Dumore hand grinder runs at 38,000 rpm unloaded.

For this operation the clapper block has to be locked to the shaper head. This is done by drilling and tapping the clapper block with a substantial socket head bolt. Also, the clapper stub arbor upon which the portable grinder is mounted has to be locked to the locked clapper block. This is done by drilling and tapping through the side of the clapper block into the stub arbor with a flat head socket cap screw.

Secondly, one has to make a substantial holding arm for the grinder. I made a single holding arm but a double holding arm would even be better. I used a split aluminum insert to help protect the grinder spindle housing. The insert has to be a very close fit on the grinder housing and in the split steel holding arm. Actually, all of the components have to be made without any shake when assembled and bolted together.

A heavy angle plate is bolted to the side of the shaper table which projects slightly above the top of the shaper table. The spring steel sheet itself is held by secondary (stepped) mounting blocks and clamps which are used to align and position the spring steel sheet itself. Note that both the main spring steel sheet and the cutoff section of the spring steel sheet have to be securely clamped.

Check that everything clears and the stroke of the shaper itself is set to just pass beyond the spring steel sheet on each side.

Be sure to employ eye protection and ensure that the shaper head slide operates smoothly and without shake or any side to side movement. Set the shaper table cross feed in neutral (and ensure that it is) then lock the shaper table securely. Start the grinder, followed by the reciprocating shaper ram and then feed down the shaper head very slowly.

The operation itself is very dramatic as the operating hand grinder sounds just like a jet aircraft taking off. The operation throws plenty of sparks so one needs to protect the machine ways. The small cutoff wheel(s) and mounting arbor(s) are standard Dremel accessories.

One should also have a wheel guard or high impact safety shield (not shown) as I was initially uncertain as to how all of the above would work but it does.
Attachments
358 Setup for the Precision Slicing of Blue Tempered Spring Steel.jpg
363 Overall View of Setup.jpg
359 Setup for the Precision Slicing of Blue Tempered Spring Steel.jpg

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neanderman
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Re: Machining Setup's with Few Comments

Post by neanderman » Tue Dec 05, 2017 2:46 am

Hey, is that my toothbrush?
Ed

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