Author Topic: Muncaster Grasshopper - Work in Progress  (Read 4152 times)

Online Jasonb

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Re: Muncaster Grasshopper - Work in Progress
« Reply #45 on: May 22, 2018, 07:00:39 AM »
Not sure why a jig or CNC is really needed to position the holes. The bars can just be held in the mill vice to drill and ream one end , zero the DRO and then move the required distance to the other hole. All other work can be done after that so they are easy to hold weather you decide to start with flat or round stock. Any jig will have small clearances which could cause differences but holding the actual part wont.Julius has put simple closed ends on them so it is not as though you have got split bearings on the ends of them all.

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #46 on: May 22, 2018, 12:33:57 PM »
The fixed stays are all of this form (see photo).  The round ends will have a 1/2" diameter with through hole 1/4".  The connecting shaft will be 3/8".  If I assume that each will be assembled from 3 separate parts then a jig of some sort is needed to hold the ends apart the appropriate distances.  There are 3 pairs needed with different lengths.  The cross holes must be parallel of course.

Online Jasonb

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Re: Muncaster Grasshopper - Work in Progress
« Reply #47 on: May 22, 2018, 01:22:30 PM »
If you are going for built up then yes, I was assuming made from one piece like the drawings show similar to the closed end ones in this pic

« Last Edit: May 22, 2018, 03:01:57 PM by Jasonb »

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #48 on: May 22, 2018, 03:04:20 PM »
There's a Solidworks image attached to the post. 

I suppose these could be made from bar stock with a form tool for the ends.  I don't own a ball turner, which would be easier, or else graduated cuts with a parting tool (my previous tries at this have not yielded very good spheres.

Online Jasonb

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Re: Muncaster Grasshopper - Work in Progress
« Reply #49 on: May 22, 2018, 03:13:32 PM »
You just need a rounded end tool in the lathe to do the fillet where the rod meets the ends, round over the end with file and buttons or on the rotary table and finish off with a round needle file to blend the two together

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #50 on: May 22, 2018, 03:22:30 PM »
When I got the CNC mill my rotary table went away.  Still, something to think about if other methods are unsatisfactory.

My little CNC lathe might work well for 1-piece solution in aluminum or brass, but probably not in steel.  I have a large amount of 1/2" square and hex brass to play around with.  I doubt brass would look appropriate for this model, but powdercoat would solve that.

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #51 on: May 23, 2018, 12:12:07 AM »
One last job before taking off to Belize and Guatemala for a week.  The two halves of the split beam.  Since Julius both magnified the V2 drawing and also made all the hole spacing integral mm, I didn't think it safe to just scale the V2 drawing.  So I mainly kept the V1 hole spacing and added the pockets and bosses, thus insuring (hopefully) that the engine will turn over without binding from the support rods.  I still need some cleanup of the edges when I return.





Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #52 on: June 01, 2018, 10:13:47 PM »
Back from Central America and back to work on the grasshopper.  Managed to get the first op (top profile) machined for the horizontal beams.  Still 3-4 ops left on these parts.


Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #53 on: June 03, 2018, 11:56:10 PM »
After profiling, the beams need various ops to bring to completion.  Here's one that I came up with to machine the space at the end.



Almost done here:  I spot drilled the places for the side mount holes to be able to check the fit before through drilling.



The holes did seem to line up after a made a temporary column, so I drilled and bolted it up.



Measurement showed that the right end is about 1mm low, but since the column is screwed to the base with a long 8-32 set screw it's easy to adjust the height.

Julius shows some fancy turning as the top and bottom of the column along with a slight taper in the shaft, so I'll have to see what can be done there.

Offline crueby

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Re: Muncaster Grasshopper - Work in Progress
« Reply #54 on: June 04, 2018, 01:06:00 AM »
Those columns and beams are looking great!

 :popcorn:

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #55 on: June 12, 2018, 09:41:01 PM »
Back at it in a small way.  Started on the main bearing block.  This is the bottom portion.  Started with a piece of 6061 2x1x1" and used a 3/8" carbide roughing mill to profile leaving .3mm clearance.



Then used a .25" endmill leaving a .2mm clearance.  This is so that a final profile with the top portion attached will match on both sides.  After profiling and drilling the 5-40 mounting holes, the bottom was machined to a total height of 25mm.

Shown in place on the frame.



Next time I'll start the top section.  Moving along slowly but I imagine it'll be done before Zee's engine.  Cletus' I'm not sure about.   :popcorn:

Offline zeeprogrammer

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Re: Muncaster Grasshopper - Work in Progress
« Reply #56 on: June 12, 2018, 10:47:33 PM »
Moving along slowly but I imagine it'll be done before Zee's engine.

 :cussing:

Replace the word 'imagine' with 'know' and I believe you'd be spot on.  :facepalm2:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline b.lindsey

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Re: Muncaster Grasshopper - Work in Progress
« Reply #57 on: June 13, 2018, 01:20:52 AM »
More excellent progress Kirk. Gonna  be a fine looking grasshopper for sure!!

Bill

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #58 on: June 13, 2018, 10:13:49 PM »
For the top part of the bearing block, I started with a 2x1x.75" piece of 6061 and profiled. 



Then on the Bridgeport I machined off the unwanted part and drilled the clearance holes for 8-32 screws.



Then did final profiles with the two halves attached.



Next, bored and reamed for a 3/4" hole for the bearing.





The off to the lathe to turn the bearing itself.  I couldn't find any piece of 5/8" drill rod, which if what I'd intended to use for the crankshaft, so I just predrilled it 1/2".  I do have a piece of chrome steel that measures .621";  if it turns out to be machinable I'll just bore the bearing to fit.  But in the interim, this is what we have.


Offline Craig DeShong

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Re: Muncaster Grasshopper - Work in Progress
« Reply #59 on: June 14, 2018, 09:14:21 PM »
Still folliwing along Kirk.  :popcorn:
This engine is starting to take shape.
Craig