Rons' Mastiff

I'm still here Bill. Life got in the way for a spell. Just finished up the teeny teflon buttons for wrist pins. Will take a pic soon.

Thanks for looking in Bob. There is an oil pump that I'll be tackling soon. have to make some gears for it yet and I neeed to make tool for machining spiral gears for the pump drive and contact breaker drive. The tool was designed by a guy named Chuck Fellows over at HMEM and Model Engine Maker.

As far as displaying it, I'll figure that out IF it runs. :roflmao::roflmao:

Ron
 
Here's what little bit I've got done for yesterday and today. I'm not a very fast worker.:whistle::whistle:

First I made up some little teflon buttons for the wrist pins. I got a large flat piece that had been in a limestone bin at a concrete manufacturing plant. It was supposed to help the rock slide down to the conveyor and help prevent wear on the bins I guess but it collapsed inside the bin and plugged everything up.:roflmao:Its blue in color.



DSC03075.jpg


Hers a shot with my finger in the way for scale. (Sorry about the blurry pic.)

DSC03077.jpg

What they look like after some careful carving with an x-acto # 11 blade and installed in the piston.
DSC03078.jpg

The blue rod is what I started with. I learned that to make the small pip to go in the wrist pin I had to turn it right to size first then turn the larger dia for the wrist pin bore in the piston. The stuff cuts very easy so there is no problem taking such a large cut.

DSC03079.jpg


I then did some threading on the camshaft and the crankshaft and called it a day. Need to get ready for church.


DSC03080.jpg


Hope you enjoy it.


Ron
 
Ron,
I got faith in ya brother. You will get it all together and spin it over a couple of times and it will fire right up. I didn't figger you were gonna splash lube it either. That's just too nice of an engine to not go all the way and build the pump and a distributor. I can hardly wait till it gets a test run. It can be right there with Bills P&W Radial. Were gonna have two of the coolest engines around pretty soon. Good luck and don't keep us waitin too long on your next installment of pics and build info.

Bob
 
It looks like I may have to cut some helical gears as I can't seem to source them. They are crossed 2:1 helical gears with tooth angles of 63* and 27* repectively. These gears are for the crankshaft and oil pump/contact breaker shaft to drive the ignition points.


I talked to to Hugh in New York, forum name “bytewise”, on MEM forum as he is building a Doxford opposed engine ( see thread, http://www.modelenginemaker.com/index.php/topic,1556.msg23103.html#msg23103 ).



He had to cut some helical gears with same angles as the ones I need. Anyway he told me that there was a formula in Machinery Handbook to figure which gear cutters to use cut the gears. He said you can't go by the ones to cut spur gears.


I looked up Helical gears in my Machinerys' Handbook 28[SUP]th[/SUP] Editon Large Print on page 2109. It stated that “the cutter for milling the helical gears is not selected with reference to yhe actual number of teeth in the gear,as in spur grearing, but ratherwith reference to a calculated Number N' that takes into account the effect on the tooth profile of lead angle, normal diametrical pitch, and cutter diameter.”


It gave a formula of N' = NK + QK'




K,K' and Q are constants found on pg 2110 in my book.


After much head scratching and moaning I was able to figure out how to work the formula.


Math and I go together like oil and water!


N is number of teeth and K and K' are constants from the table on helix angles and Q is from the table on Outside and Pitch Dia. Of Standard Involute milling Cutters. On the same pg.


Any way here is what I came up with.


For the 63* gear the formula is:


N' = (8 x 10.687 ) + ( 53.76 x 3.852 ) = 85.50 + 207.08 = 292.58 say 293 which is a # 1 cutter.


( I round up or down to get to 2 decimal points in the totals)


For the 27* gear it is:


N' = ( 16 x 1.414 ) + ( 53.76 x .260 ) = 22.62 + 13.98 = 36.6 say 37 which is a # 3 cutter.


These are for 32 DP cutters.


Could some one check my math and see if I did it right?


It looks like I'm going to need to buy some cutters. Hopefully I can sell a couple of never used Gas Model Airplane Engines for large scale models I have and will probably never use, to raise the funds for the cutters.


Haven't done to much as of late. Been trying to figure these gears out.



Ron
 
I have been doing manual machine work for 27 years and it never ceases to amaze me at the quality of the work that you guys turn out. Great job!
 
Thank you "eightball", it's greatly appreciated.

Ron

- - - Updated - - -

I debated on whether to put this here or in “Shop Made Tooling”. (Mods if this is the wrong place please move it.)


I need to make some helical gears for the this engine. I can order them from England but they want over $80.00 for the pair.

A guy named Chucks Fellows on MEM and HMEM forums designed a fixture to turn helical gears so I made the fixture and the arbors and gear blanks in preparation for the arrival of my gear cutters I ordered late last week. They are supposed to be here Wed or Thurs.



The gears are Crossed Helical Gears and have a helix angle of 27 degrees on one and 63 degrees on the other. They are 2:1 ratio but are the same overall size,.6250. The crankshaft gear has 8 teeth and the oil pump/distributor gear has 16 teeth.


I only cut one other set of gears and they were just plain spur gears. This is going to be a whole new ball game.:panic::panic:



Here's the parts to the fixture.


http://s661.photobucket.com/user/ozzie46/media/DSC03090.jpg.html]DSC03090.jpg[/URL]


An assembled view. There are 2 arbors because the bores on the gears are .3125 on one and .250 on the other.


http://s661.photobucket.com/user/ozzie46/media/DSC03091.jpg.html]DSC03091.jpg[/URL]




And a pic of it mounted in the vice.


http://s661.photobucket.com/user/ozzie46/media/DSC03089.jpg.html]DSC03089.jpg[/URL]



I turned the long shaft between centers and discovered my lathe was turning a slight taper.

When I checked it I found out it was about .007 over 10 inches, :angry::angry::angry::angry:so I spent today aligning the headstock and tailstock. My test bar showed .000 over 10 inches after aligning them.:thumbsup:



I know tomorrow with temperature changes it probably won't be that good but was today.




Ron
 
Think of the helical gear as a spur gear with a twist. It won't be as bad as you think. I like your tooling approach. Should do just fine.

"Billy G"
 
Ron;

Do you have a link to that cutting fixture. I need to make them for a Turboprop Project.

"Billy G"
 
Here you go Bill.

Post # 12 has some videos of Chuck making some gears.

Post #17 has the pdf. file.

When ever I download from the site I have to right click and use "save link as".

You may have to join to get the file, not sure. If you don't want to let me know and I can e-mail you a copy of my file if you want.

http://www.modelenginemaker.com/index.php/topic,2035.0.html


Ron
 
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