Author Topic: Muncaster Grasshopper - Work in Progress  (Read 22410 times)

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #165 on: December 10, 2018, 10:18:51 PM »
Over a year ago I bought a secondary high-speed spindle and made a mount for my CNC mill.  But I've never actually used it.  Now that I want to "engrave" the grout lines in the simulated brick of the engine's sub base, I decided to hook it up for some testing. 

Since the collets of the spindle limit me to 1/8" diameter tools, I can't use an edge finder to directly establish X/Y zeros on the stock.  To do this, I mounted a piece of scrap aluminum in the vise and used the spotting drill in the spindle to make a dimple.  Then zeroed the DROs.



Next I mounted a pointed center finder in the main spindle, lowered it by eye into the dimple, and then with the finder turning used the fine jog keys to determine by touch when the finder was centered.



The new values in the DROs show me the offsets between the two spindles.



I then mounted some scrap that I had used to test powder coating and used the spotting drill as an engraver.  The first two lines were at DOC of .01" and .02", 11K RPM and 100 IPM feed.  The .02 DOC looked about right for width of cut, but the slot was burred.  A third line at 20K RPM with the same feed rate gave a cleaner cut, and a fourth at 30K RPM showed no difference.



My previous test using a 1/8" endmill and 4000 RPM max on the main spindle resulting in a less than clean edge of the powder coat and a fairly slow feed rate.  This setup should be much less time to mill.
« Last Edit: December 11, 2018, 12:08:49 AM by kvom »

Offline crueby

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Re: Muncaster Grasshopper - Work in Progress
« Reply #166 on: December 10, 2018, 11:05:25 PM »
Interesting setup, should open up all sorts of possibilities.


 :popcorn:

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #167 on: December 18, 2018, 09:53:10 PM »
The aluminum I ordered for the sub-base finally showed up Monday, apparently delayed by the Xmas rush.  It will have the same dimensions as the regular base, that is 13x3.55" and 3" high to clear the flywheel.  The sides are 6061, 3x12x1/4, while the ends are1/2" thick Mic6 3x3.55" carved out of a piece of scrap left from the hummingbird build.

The 4 pieces will be joined by 1/16" diameter SS locating pins.  After machining all to size, I needed to drill holes for the pins.  The ends provided no problem, but the sides needed the holes drilled in the ends.  Here's the setup on the CNC mill for doing this:



I didn't need CAM to do this, as the gcodes for drilling are easy to just type in individually.

Here are the 4 pieces ready for the next step, which is powder coating a shade of red-orange to resemble bricks.


Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #168 on: December 20, 2018, 11:10:56 PM »
Ready for some brickmaking.  Powdercoat the four sides of the base.



Cutting mortar lines with the hi-speed spindle and an engraving bit.



Rough assembly with locating pins to gauge general appearance.  I still need to engrave the mortar lines on the sides of the narrow ends.



I'd like to fill the lines with some white paint: spray on, wait a few seconds, then wipe leaving paint only in the grooves.

Offline Ye-Ole Steam Dude

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Re: Muncaster Grasshopper - Work in Progress
« Reply #169 on: December 20, 2018, 11:37:51 PM »
Hello kvom

That looks beautiful and will highlight the engine. :ThumbsUp: :ThumbsUp:

Have a great day,
Thomas

Offline crueby

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Re: Muncaster Grasshopper - Work in Progress
« Reply #170 on: December 21, 2018, 12:20:02 AM »
Great color combination, beautiful engine!

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #171 on: December 27, 2018, 07:20:40 PM »
Time to start on the governor, although it may take a while.  The lower portion of the "drive train" has a horizontal shaft aligned with the crankshaft driving a vertical shaft via two bevel gears.  Using the gross dimensions from Julius' model, I found a matching gear and pinion at Stock Drive Products.  To verify how the gears would fit with the lower bracket, I downloaded the provided Step (.stp) files from the website, and had Solidworks convert these into part files.  Then I joined them with the bracket into an assembly.

I'll need to modify the bracket slightly to accommodate the collar of the large gear, but otherwise they look good.

Offline b.lindsey

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Re: Muncaster Grasshopper - Work in Progress
« Reply #172 on: December 27, 2018, 10:46:24 PM »
That base turned out very nice Kirk.  The whole project is just beautiful.

Bill

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #173 on: December 28, 2018, 09:28:55 PM »
Today I made a start on the bracket.  It cannot be machined exactly as Julius modeled it, but in general it's close.  I took a piece of 1.5" square brass bar, squared it up with a face mill, and then made the first op on the CNC mill.



Second op was to profile the front and drill the mounting holes (5-40 clearance) and the 3/16" hole for the pinion shaft through the bottom.



Then cleared out the front to a depth of 19mm. Once my gear arrives I'll further remove stock to provide proper gear mesh.  Here's where it will stay until the gears arrive, probably around Jan.4.


Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #174 on: December 28, 2018, 09:44:41 PM »
The connection between the large gear shaft and the crank pin is interesting.  Here's a closeup of the SW model:



The link has an eye on one end that rotates freely on the crank pin.  The other end passes through a hole in the shaft and is able to slide within it as the crank rotates.  This allows the gear shaft and crankshaft to be slightly misaligned.

Online Kim

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Re: Muncaster Grasshopper - Work in Progress
« Reply #175 on: December 28, 2018, 10:16:46 PM »
That is an interesting setup. I've not seen that before.

Nice work on the bracket too, Kvom!
Kim

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #176 on: December 30, 2018, 04:52:59 PM »
The upper bracket that holds the governor and attaches to the horizontal beam presents problems for fabrication.  Here is the bracket as designed by Julius.



I modified it slightly to accommodate the 3/16" shaft needed for the pinion gear, and uploaded it to Shapeways to see if it could be printed.  No go, as apparently there's too many unsupported features.  After some cogitation, I came up with a two piece solution as shown here.



The bracket in grey is relatively straightforward, while the arm will require some fixturing.  I tried the arm by itself in Shapeways and still a nogo.

Offline crueby

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Re: Muncaster Grasshopper - Work in Progress
« Reply #177 on: December 30, 2018, 05:15:04 PM »
That looks like a part crying out for some silver soldering of arm to rods, then drilling the rods.

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #178 on: December 31, 2018, 12:44:14 AM »
That looks like a part crying out for some silver soldering of arm to rods, then drilling the rods.

But that's because you don't have the magic green button and have to mess with danger chemicals and fire.   >:D

I've been playing with CAM  this afternoon and have a fairly straightforward way to CNC the arm part.  I'll provide photos if it works and excuses if it doesn't.

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #179 on: January 01, 2019, 12:44:35 AM »
Did work on the bracket this afternoon.  Step one is cutting 2" of 1x1" brass bar on the bandsaw, then into the vise with a square to ensure it's upright.



Next, milling a 1/2" round boss:



Now it can be held securely in a 5C collet;  face the end.



Next, mount the collet in a square collet block with the sides of the bar parallel to those of the block.  Mount in the mill vise with a vise stop, and establish the zero coordinates:  Y centered on the block, X at the free end of the bar, and Z at the centerline of the bar.  By doing this the collet block can be turned in the vise and all 3 coordinate zeros stay the same.  To find Z0 for each tool, I touch off on a 1" gauge block setting on the collet block.  Since the collect block is 1.725" square, I can set Z to half of that plus 1 inch.

First cut is the side profile using a 3/8" 4-flute endmill.



Rotate the collect block and cut the partial top profile.  The drill and ream the 5/16" vertical hole.





Turn the collet block to drill and ream the 3/16" horizontal hole.



Finally finish both sides of the "neck":



The remaining work is to separate the piece from the remaining bar and finish profiling that end.