Author Topic: PM Research Engine Number 1  (Read 6549 times)

Offline Flyboy Jim

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Re: PM Research Engine Number 1
« Reply #90 on: February 10, 2020, 02:49:51 AM »
Well done Stuart.  :ThumbsUp: Mounting fixtures really help for cast parts.

I too like to find the center (or work from the edge with an edge finder) instead of transferring holes from one piece to another. More accurate I think.

I need to spend some time with your chart to figure out how to use it to locate holes (other than 2 or four holes). So far, for that many holes, I've been able to mount the part on my RT, locate the center, dial in the radius and rotate for the holes. I don't see how I could of done that with your casting.

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline propforward

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Re: PM Research Engine Number 1
« Reply #91 on: February 10, 2020, 03:38:04 AM »
I agree Jim - itís very satisfying to make parts to tolerance individually, and for them to then fit together correctly.

On those charts, you can get the same result by doing some simple trigonometry. The chart simply has all the trig distilled into factors that you can then use with the bolt circle to generate the X, Y co ordinates. I think this used to be a very common way of making bolt circles, but rotary tables are so much more readily available that the method isnít used so much. Good one to have in your back pocket for situations like this though.
Stuart

Offline gary.a.ayres

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Re: PM Research Engine Number 1
« Reply #92 on: February 13, 2020, 09:33:36 PM »
Looking good. One can see the engine beginning to emerge...

 :ThumbsUp:

gary

Offline propforward

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Re: PM Research Engine Number 1
« Reply #93 on: February 14, 2020, 03:35:58 AM »
Thanks Gary, lots to do yet, but I must admit that being able to test fit the cylinder and seeing it in place was a real boost.
Stuart

Offline zeeprogrammer

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Re: PM Research Engine Number 1
« Reply #94 on: February 14, 2020, 12:03:23 PM »
Nicely done.  :ThumbsUp:

In the 10th photo...what is that tool holding the center drill? The tool is being held by a collet.

Don't you love that power feed?  ;D
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline propforward

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Re: PM Research Engine Number 1
« Reply #95 on: February 14, 2020, 01:47:19 PM »
That is an ER11 collet holder. It has a 1/2" shank, and the diameter of the collet nut is not much bigger than that. I got it because it gives me more access to small parts  than the standard drill chuck, which often gets in the way of clamps and so on, plus it runs a heck of a lot more concentric than the standard drill chuck. Only issue is I need a few more collet sizes to cover more drill sizes. It's great for some of the small end mills and the center drills etc. But with a few more collet sizes I think this is going to be a very nice tool to have on hand. I bought it from Shars, but I think little machine shop has them, and certainly plenty of ofther tool suppliers have them. Travers for example. Not too expenisve either.

I freely admit that purchasing it was buying my way out of problems when I could likely have applied myself a bit more and found other fixturing means with what I have on hand, but at the same time this is becoming my main hobby now, so selling my bikes and getting a larger variety of tooling is just part of the fun for me. Eventually I'll add a DRO as well for the mill, but I feel I haven't quite "earned" that yet. But I'm getting there. :D


Yep, I sure love the power feed!
Stuart

Offline zeeprogrammer

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Re: PM Research Engine Number 1
« Reply #96 on: February 14, 2020, 02:19:44 PM »
Thanks. What is the collet holding? How is the center drill held?

but I feel I haven't quite "earned" that yet. But I'm getting there. :D

"Earned"? Of course you have.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline propforward

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Re: PM Research Engine Number 1
« Reply #97 on: February 14, 2020, 02:52:08 PM »
Thanks. What is the collet holding? How is the center drill held?

The holder has an internal taper and a threaded nose, and then there is a sprung collet which inserts into that, which is compressed into place by the collet nut. Like all ER series collets, the collet clicks into place in the collet nut, so that it is forced out of the taper when removing the nut. It's exactly the same system as any other ER collet set - or basically any collet style, but is simply a miniature version, capable of holding tools up to 1/4" in diameter.

Quote
"Earned"? Of course you have.

Weeeeeeeeeell, I have been diligent on my handle turning, and allowing for backlash, and have made components with bolt patterns that fit together properly without using one part to transfer a bolt pattern to another part, so in a sense yes, I have convinced myself that I do understand how to drive the tool properly. But on the other hand, the DRO set up I really want is about $2K, (there are less expensive ones but this one has some very nice features), and I have to wait until I've sold one of my few remaining motorcycles, or save up for it. :D
« Last Edit: February 14, 2020, 03:06:10 PM by propforward »
Stuart

Offline propforward

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Re: PM Research Engine Number 1
« Reply #98 on: February 22, 2020, 10:51:48 PM »
Back in the shed today. I've not been able to get shed time for a couple of weeks, with other things going on, but some of those things were fun too, so it's all good.

I made a pin to fit to the center hole, with the idea of using it to locate the hole and therefore allow me to mill the rails accurately.



Then I started milling the insides of the rails.



After an initial cut, I located the center of the hole again, and took a measurement to the top of the casting surface of the rails, to get a feel for how much I was going to need to remove.



That technique worked well enough, but in the end I actually touched off the bore of the hole with the height gauge rather than using the pin.

Anyway, cleaned up the rails





I made a bit of a meal of this, with multiple set ups I didn't need, if I'd actually thought through it a bit better. I ended up taking the casting out, and turning it sideways to check the inside rail to bore center dimension using my height gauge. I was a bit worried I'd messed up because at this stage the rails were very uneven. However, it turned out I just needed to take more off one rail.

I set it all up again, and finished up.





Then drilled and tapped the upper rail mounting holes.





As far as I can tell, I'm within .001" on the width of the rails, with the centerline of the rails maybe within 0.003" of center line of the bore, and height of the rails is within .001" of nominal, so not a bad go at it.

Got to think about how to do the bearing caps and crankshaft bearing holes now, so I may move on to something else tomorrow while I mull that over.
Stuart

Offline zeeprogrammer

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Re: PM Research Engine Number 1
« Reply #99 on: February 22, 2020, 11:35:44 PM »
Looking good.  :ThumbsUp: :popcorn:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Flyboy Jim

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Re: PM Research Engine Number 1
« Reply #100 on: February 23, 2020, 02:33:39 AM »
Great progress and documentation Stuart.  :ThumbsUp:

I've been a little sidetracked on my PMR #5 build as well. We've had some nice, almost Spring like, weather here, so got caught up on my Fall yard work and a head start on Spring gardening.

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline crueby

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Re: PM Research Engine Number 1
« Reply #101 on: February 23, 2020, 02:43:51 AM »
Fantastic results!  :popcorn: :popcorn: :popcorn:

Offline gary.a.ayres

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Re: PM Research Engine Number 1
« Reply #102 on: February 26, 2020, 06:24:23 PM »
Taking shape nicely...

 :)

Offline Don1966

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Re: PM Research Engine Number 1
« Reply #103 on: February 26, 2020, 07:34:51 PM »
Great results and great photos!


 :popcornsmall:
Don

Offline propforward

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Re: PM Research Engine Number 1
« Reply #104 on: Today at 01:34:07 AM »
Thanks everyone, I do appreciate you looking in. Got a couple of commitments that may keep me from the shop this weekend, but hopefully back to it very soon. This casting has been a fun exercise, pushing me a bit more, and I have really enjoyed it, so very much looking forward to picking it up again.
Stuart