Author Topic: 1st I.C. build "Tiny"  (Read 75027 times)

Offline steamer

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Re: 1st I.C. build "Tiny"
« Reply #210 on: May 04, 2017, 11:59:33 AM »
Harold halls unit is a good one to build....probably the simplest dividing/indexing head build I've seen

As is Rudy's.     

If you have a 40 tooth change gear, the rest is not that hard to cobble together with some work.....

Glad to help if I can Bob....

Dave
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Offline 90LX_Notch

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Re: 1st I.C. build "Tiny"
« Reply #211 on: May 04, 2017, 01:06:39 PM »
I thought about cobbling up something Dave.  I remember Tel posting a real simple one.  If it comes down to it, that's what I'll do. 

I look at it this way, I'm in this hobby for the long haul and a BS-0 Dividing Head makes sense.  I just don't want to layout money for a Chinese "kit".  I want something that works right out of the box and is accurate.

-Bob
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Offline gbritnell

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Re: 1st I.C. build "Tiny"
« Reply #212 on: May 04, 2017, 05:31:46 PM »
Hi Bob,
I have a Vertex -0- dividing head that I bought off Ebay quite a few years ago. I'm quite happy with it. Looking at the current prices on Ebay shows that what's available is quite pricey. You might be better off to get a horiz-vert rotary table.
gbritnell
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Offline 90LX_Notch

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Re: 1st I.C. build "Tiny"
« Reply #213 on: May 04, 2017, 06:51:54 PM »
Thanks George.  I figure that a dividing head will be more versitile in the long run.  Yes, they are pricey.   I noticed that the Grizzly BS-0 jumped $100.00 in eight years (old catalog, $299.00 vs website, $399.00). 

-Bob
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Offline Doc

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Re: 1st I.C. build "Tiny"
« Reply #214 on: May 05, 2017, 12:43:58 AM »
Bob
Things are looking good nice job!

As for gears.
 You can make the gear on the cheap as I call it. I've used this method a few times and has worked very well.
Here is a video of what I'm referring to.
<a href="https://www.youtube.com/watch?v=gKlFEVWEtuI" target="_blank">http://www.youtube.com/watch?v=gKlFEVWEtuI</a>

With this method the bigger the dia you use for the index the more accurate it is and there is no limit to the number f teeth and gear size you can make. 

Offline 90LX_Notch

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Re: 1st I.C. build "Tiny"
« Reply #215 on: May 05, 2017, 04:04:56 AM »
Thanks Doc.  I watched your video and the results speak for themselves. Impressive.

-Bob
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Offline 90LX_Notch

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Re: 1st I.C. build "Tiny"
« Reply #216 on: May 08, 2017, 05:20:01 PM »

Crankshaft:

First order of business is holding the crank offset by .250.  I set it up in the four jaw and didn't like the looks of it; so, I went about making a fixture.  The fixture is pretty straight forward and was designed for future use for other crankshafts.  There is a center for centering, then a spot is made for the required offset.  The spot is then picked up using the floating center method.  The required diameter for the crankshft is then produced.  A threaded cross hole is used to hold the crank by having a set screw push a .125 diameter brass plug against it.  By using a threaded crosshole, future holes of different sizes and offsets can be added. (That's the idea anyhow.)

The fixture is simply centered on the faceplate using the drilled center.

A parting tool was ground with the necessary reach for the throw.  The crank was then set up in the mill and a bulk of the waste material was removed.

The crank was then placed in the fixture and the turning of the crank pin began.

All for now....


-Bob
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Offline b.lindsey

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Re: 1st I.C. build "Tiny"
« Reply #217 on: May 08, 2017, 05:44:08 PM »
Another milestone Bob. Happy you are getting some shop time in too.

Bill
« Last Edit: May 09, 2017, 01:33:01 AM by b.lindsey »

Offline Tennessee Whiskey

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Re: 1st I.C. build "Tiny"
« Reply #218 on: May 08, 2017, 08:57:50 PM »
Nice looking crank Bob. How did you secure it in the fixture? I watched one of Stefan Gotteswinter's videos on a modified Keats type fixture this morning. It's a multi position plate much like your dedicated offset one.

Cletus

Offline 90LX_Notch

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Re: 1st I.C. build "Tiny"
« Reply #219 on: May 09, 2017, 12:19:15 AM »
Bill- I'm happy to be at this milestone.

Eric- The crank is about half finished at this point. There is a .1875 diameter hole reamed in the fixture .250 from the center.  The crankshaft is inserted into this hole.  Perpendicular to this hole is a 10-32 threaded hole.  A 10-32 setscrew pushes a piece of .125 diameter brass against the shaft locking the crank in place.  The fixture is toe clamped to the faceplate.

-Bob
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Offline Flyboy Jim

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Re: 1st I.C. build "Tiny"
« Reply #220 on: May 09, 2017, 03:12:40 AM »
I like this fixture Bob. I think I have the drift, but would love to see some more pictures of the setup. The fixture plate for my Sherline RT looks a lot like your fixture plate, so I can now see a double duty use for it.

Also, I'm curious as to what your reservations were about using your 4 jaw chuck?

Thanks, Jim
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Offline 90LX_Notch

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Re: 1st I.C. build "Tiny"
« Reply #221 on: May 09, 2017, 10:25:39 PM »
Jim-

There is a small radius on the shaft where it meets the web of the crankshaft.  This radius would prevent the web from sitting flush to the face of the chuck jaws.  I felt that this would cause a lot a flexing during an interrupted cut and would increase the chance of the tool binding and ruining the crankshaft.


The hole in the fixture has a shallow counter bore to allievate this problem.  The main reason for the fixture was to provide a solid face for the crankshft web to butt against.

If you need any other view let me know and I'll take some other pictures. 

-Bob
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Offline 90LX_Notch

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Re: 1st I.C. build "Tiny"
« Reply #222 on: May 09, 2017, 10:43:41 PM »
Crankshaft continued:

The crankpin width was checked with a drill blank and the pin diameter was finished turned.  Next the .250 diameter bosses were turned. 

I can admit that had my worries that the a single setscrew would be up for the task of holding the crankshaft for the turning of the crankpin.   But, the brass plug held it firm without marring the shaft.  Now that I know it works, I have plenty of room to add holes as the need occurs for other crankshafts of different dimensions.

Now I just need to mill the counter weights and the Crankshaft will be done.

-Bob
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Offline b.lindsey

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Re: 1st I.C. build "Tiny"
« Reply #223 on: May 09, 2017, 10:59:26 PM »
Bob, I put a shallow recess in the face of my fixture that was a slip fit to the web OD. This was insurance against the crankshaft turning in addition to the setscrew, but would make the fixture less versatile for future use.

Bill

Offline 90LX_Notch

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Re: 1st I.C. build "Tiny"
« Reply #224 on: May 09, 2017, 11:30:35 PM »
I thought of that Bill but I don't think it would actually make a difference because the od is concentric to the shaft od.   Therefore, the od will never actually make contact with pocket/counterbore in the event of the shaft slipping. 

I also considered just putting a pin in the fixture face that would prevent the crank from moving by locating in a hole in the webb.  The hole would later be milled away when the counter weights are machined. 

-Bob
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