Author Topic: Chris's Marion 91 Steam Shovel  (Read 247749 times)

Offline Don1966

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Re: Chris's Marion 91 Steam Shovel
« Reply #645 on: February 03, 2018, 11:52:11 PM »
Damn fine work is all I can say Dog. Keep it up and the photos coming I do enjoy this.


 :cheers:
Don

Offline Bluechip

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Re: Chris's Marion 91 Steam Shovel
« Reply #646 on: February 04, 2018, 10:53:31 AM »
Hold something with a sharp point on it in the chuck. Line the gear cutter up with that to center it. That's what I do.
Agreed, that's what I do for larger gears.

Ah!   Thank-you Gents ...
I was faffing about trapping the gauge between the blank and cutter.   :headscratch:
Didn't think about making one of them a point.
No excuse, the BS0 head is socketed 2MT, I can use a centre.
But then I can never see the  obvious.    :embarassed:

Very impressive build, Chris     :praise2:   Don't know how you persevere.   

Dave
« Last Edit: February 04, 2018, 10:57:45 AM by Bluechip »

Offline Jo

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Re: Chris's Marion 91 Steam Shovel
« Reply #647 on: February 04, 2018, 12:24:57 PM »
I measure the width of the cutter and half it = A. I measure the diameter of the gear blank and I half it = B. I then get a height gauge and measure the top of the work = C.

I now subtract B from C and add A = the required height to the top of the gear cutter. Using the height gauge I set the top of the gear cutter using the knee of the mill  ;)

Jo

Usus est optimum magister

Offline Bluechip

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Re: Chris's Marion 91 Steam Shovel
« Reply #648 on: February 04, 2018, 01:11:15 PM »
Hi Jo

That sounds good ...  :ThumbsUp:

What I did, amongst other things, was to establish the centre height of the BS0 which is 3.992". ( Claimed as 4"  :headscratch:  but I'll let them have that ).

Then did a similar process to you except .....  fly in ointment ....  my set of 0.75 Mod cutters vary in thickness. ( ex-RDG )  ( 5.60mm to 5.22mm, higher cutter #s. being thinner ).
So  if I were to make gears using different number cutters I would have to reset the Z axis.  But in retrospect, no big problem.  :ThumbsUp:
I had read of the 'calibrated eyeball / feeler gauge' method and wondered if it was as effective but quicker.
Will have to have another go sometime, back to de-coking greenhouse. Now mercifully almost clear of brown stuff.   :whoohoo:

PS I did produce a pair of 32T 0.75 Mod gears in 12mm PVC which seemed to mesh rather nicely much to my surprise.  :)

Dave





Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #649 on: February 04, 2018, 03:42:02 PM »
Hi Jo,


The only problem I have with that method is some of my cutters don't appear to have the cutter tip centered in the disc. The profile of the cutting portion is symmetric, but the center disc is a little thicker on one side. Thats why I like to center on the tip instead.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #650 on: February 04, 2018, 08:07:05 PM »
This morning I ground the cutter for the gear rack - drew some 20 degree lines on the tool rest on the slow speed grinder with a fine wheel, and took down a 1/4" HSS tool blank to shape. Here is what it looks like:

And the setup on the mill, with the head turned sideways. I had to remove the riser block under the column, and am using the vise since the bit won't reach the longer notched table I made for the booms. So, I'll use the vise, and step it over every couple of inches.

I pre-calculated out and made a list of the handwheel positions from the diagram, so that I could just concentrate on the positions rather than having to do the math in my head for a 0.07421 move every time. Here is the start of a test piece, seemed to go well:

and the rest of the test piece:

The gear moves smoothly over the rack, so the calculations must have been correct.   :cartwheel:

Next up, make the longer bars....

Just thinking, with the rack blanks bolted to the booms, I can make the full length set of cuts, since the booms will support the bar. That will save having to line up the last slot when moving the bar in the vise..... Should work, will find out!
« Last Edit: June 16, 2018, 08:57:39 PM by crueby »

Offline Don1966

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Re: Chris's Marion 91 Steam Shovel
« Reply #651 on: February 05, 2018, 01:49:31 AM »
Chris that is awesome dog I .........like.........  :Love:


 :drinking-41:
Don

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #652 on: February 05, 2018, 01:56:16 AM »
Chris that is awesome dog I .........like.........  :Love:


 :drinking-41:
Don
Thanks Don, Glad to see you along for the ride!

 :cheers:

Offline Kim

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Re: Chris's Marion 91 Steam Shovel
« Reply #653 on: February 05, 2018, 06:10:29 AM »
Interesting way to do the rack.  So you didn't make infinitely large buttons to shape your tooth profile?  You just ground it free hand?
Kim

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #654 on: February 05, 2018, 02:02:13 PM »
Interesting way to do the rack.  So you didn't make infinitely large buttons to shape your tooth profile?  You just ground it free hand?
Kim
Thats right, when I looked up the formulas for rack teeth, found out that for involute gears, the form of the rack teeth is a simple straight sided tooth, so all I needed was to grind a flat 20 degrees off center on each side, then a touch to flatten the tip, checked the width of that with a dial caliper. A lot simpler shape than I had expected.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #655 on: February 05, 2018, 07:46:23 PM »
Today I got a start on cutting the actual gear racks. First one was drilled/threaded/bolted on with some threaded rod and nuts, rod going halfway through the rack blank so as not to interfere with the gear teeth. Set it up in the mill, holding up the far end on a machinist jack to make sure the weight of it did not make it slip down, and started cutting teeth. In this shot you can see why I needed the longer fly cutter, to clear the headstock and motor pulley as the rack was moved along:

Here it is with all the teeth cut. The last section will get a thicker piece on it, to form a stop for the gear so that the boom cannot come all the way out of the small gear and traveller.

So, one rack down, one to go, then get the end stops formed. I also need to make some stepped nuts, so that I can bolt in the racks from the other sides and then mill off the top of the nuts.
« Last Edit: June 16, 2018, 08:57:51 PM by crueby »

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #656 on: February 05, 2018, 11:44:27 PM »
Got the other gear rack cut this afternoon (looks just like first one, so no extra picture), ready to start on the nuts for attaching them to the booms. Looks like a very cold/snowy week coming up, so good time to stay indoors and play in the shops!

Offline jschoenly

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Re: Chris's Marion 91 Steam Shovel
« Reply #657 on: February 06, 2018, 01:52:46 PM »
My current project, the Cornwall Forge engine wants square nuts. I have not found a good way to do that yet.

Ron - Gang tool plate and mach4 mini lathe rigid tapping?  ;)
Jared
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Offline kvom

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Re: Chris's Marion 91 Steam Shovel
« Reply #658 on: February 06, 2018, 03:13:45 PM »
If I needed to make a quantity of square nuts, I'd try to do it on the lathe with square stock in a 5C collet.  Drill and tap, then part off each one.

Offline wagnmkr

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Re: Chris's Marion 91 Steam Shovel
« Reply #659 on: February 06, 2018, 10:59:53 PM »
Same as Kvom ... square stock in a 4 jaw ... drill about 1 1/2 to 2 inches ... tap and part off and repeat. Done it many times and yes, it is mind numbing after a bit, but three or four sets a day can make quite a pile of square nuts.

Tom
I was cut out to be rich ... but ... I was sown up all wrong!