A Wallaby of my own.

[gmac]

Mosey;

From someone who's ..... duh.... yes I'm a noob and I'm learning! The Toolmakers Button Method;

http://modelengineeringwebsite.com/holes1.html

<a href="https://www.youtube.com/watch?v=IPV54iNBo1M" target="_blank">http://www.youtube.com/watch?v=IPV54iNBo1M</a>

Chapter 1;

http://www.knucklebusterinc.com/downloads/freeEbooks/Modern_Toolmaking_Methods_GO.pdf

Cheers Garry

[steamer]

Well Garry....almost.

I'm not using the button to locate, but to guide.

Let me explain.

The button I am using is .25" diameter, on the big end ....and is .125 on the small end.   The button is located in the bolt hole location which are drilled first...in this case in 5 locations..   Now the "casting" has a semicircular boss surrounding the bolt, that needs to be machined...which if you have a CNC....is a piece of cake....but I don't!....AND I don't have a circular interpolation option on my very simple DRO.   So ....what to do.

I could set the part up 5 times on a rotary table, and machine the radi.    Seems like a lot of work.

Or ....I can do it with the button method!

Make up the botton as described above...with a close fitting .125 shank and the radius equal to the radius of the boss.  The shank should fit fairly closely...but spin easy in the hold

Now...from the outside of the part...plunge into the part and dial into the part toward the center of the boss...and slowly come up to the OD of the bushing.    When the milling cutter touches...the button will spin rapidly....now pay attention to which side of the center your on...move the Y....until the bushing spins....then move the X away...until it stops....move the y again..until it spins....move the X until it stops...pay attention to the direction!

This method will give a "circular interpolation" of the radius of the boss...close enough....to clean up with a file to a nice radius...

Here's the head I did earlier




and one with the "bushing" laying on top of the part



Now I did use the "Button locating method" when I made the oil pump for this engine....and there I used a pair of buttons to locate the pump gears.....but the need was different....

Dave

[gmac]

Dave;
....and the other shoe drops... I wondered about Jo's question about spinning. But I'd never heard of this method before. Thanks for the education!! Seems like a process fraught with trouble for a noob not on his game with spinning the X and Y handles

Cheers Garry

[steamer]

Dave;
....and the other shoe drops... I wondered about Jo's question about spinning. But I'd never heard of this method before. Thanks for the education!! Seems like a process fraught with trouble for a noob not on his game with spinning the X and Y handles

Cheers Garry

Easy peasy......you go slow....and you think carefully before you do it!....no sweat!

Dave

[steamer]

Oh and even the ones who aren't noobs ...have bad days...and scrap parts....its part of the gig!.

Dave

[gmac]

....one handle at a time I take it! Thanks Dave. I just went and reread the whole thread and there on page 21 was.....yup...this subject! You may have motivated me to try gear cutting using your style of cutter as well!

Cheers Garry

[swilliams]

Nice Dave

I like this button method, it a good idea

Steve

[Mosey]

Thank you ,Dave. I'll add this to my repertoire of exciting techniques to try when the part is already compromised! Very clever!
Mosey

[steamer]

Hey I actually did something in the shop today!....vacuumed the floor after too!

Put the gear case cover back up and started whittling the outside....again, as an experiment...I tried the button profiling method for the 1.75 diameter....and it worked!





Next I put it back up in the lathe to start facing the other end.


and then back in the mill...where I cut back enough to part it from the mother material....it looks ragged at the moment...but it came out pretty good, and the edges will clean up nice with a belt sander and a file.

Dave

[Don1966]

Hi Dave, glad to see some progress on this one. I like your button method and will be trying it out on my next venture. By the way is that aluminum or steel your using, it's had to tell?

Don

[swilliams]

Love it Dave. Really making great use of that button method, you've put me onto one of the best things I've picked up in some time.

Steve

[steamer]

Glad you like it.....here's some observations

Make the bearing shaft portion small in diameter, and as long as possible...the more torque you put into turning the button the more it wants to lift...which could be a catastrophe!  making the axle portion of the button small reduces the torque required and minimizes lift ....I think reverse helix end mills might help, but I was successful with conventional....though I would NOT use fast helix cutters!

Just kiss the bushing...be patient and let it talk to you...you'll know when your on it.  Go Slow!

Don't get distracted!....it's easy to forget which way to turn the screws if you are...

If you have a rotary table set up like a GHT table...it will probably be faster...if you have a lot a blends though....it works pretty well!

Dave

[swilliams]

You could possibly run the machine in reverse to pick up the button??

Steve

[steamer]

No.....your cutting right up to the button..and when it starts turning...you stop.

I made the cuts .44 deep up to the button.

A quicker way would be to use a DRO with a bolt pattern feature, set the number of holes to some very large number, and nibble your way around....which would not need a button...

Dave

[swilliams]

Gotcha