setting up boring head

[firebird]

Hi

I need to machine a radius into the side of a cast iron cylinder (please see my portable engine post).

I'm going to use a boring head in the milling machine. How do I accurately set the correct radius.

Cheers

Rich

 

[Jasonb]

Clamp a bit of scrap metal opposite the face and cut a littel of the face and the scrap, measure until you hit dia and then advance the tool into the cylinder.

Not one of my engines but I have used the method

J

 

[Tin Falcon]

I have always set my boring bar the same way I get an accurate dimension on the late. start with a rough sized hole . take a cut, measure, advance the micrometer gage on the bb. cut again measure again repeat until you have the dimension you need. Take spring cuts when you are close.

you can take some measurements of you boring bar and do some math but without seeing what you have or knowing the radius I would just be speculating.
Tin

 

[firebird]

Hi

Thats the sort of thing I need to do Jason. I think you are referring to boring a hole Tin?

I have just nipped out to the work shop and quickley mocked up what I need to do.

I need to find out how I set the tool to give me a radius of 2.214 inch.

Cheers

Rich

 

[Dave G]

The most accurate method is to use a piece of stock as Jason has described, but another method I use when accuracy isn't of utmost importance is to edge find a soft straight edge in the mill, set zero and then move off the radius of your finished dia. Install your boring head in the spindle of the mill and attach your boring bar to the boring head and then rotate the boring head by hand and adjust the dia of the boring bar untill you just lightly touch the straight edge you zeroed off of. Your boring bar will now be very close to the finished dia you desire. Once the radius is set, move the table in the direction you want to cut without disturbing the boring bar setting. Plunge cut in small increments until you have the desired depth of radius. This is not the most accurate way but is quick and easy for jobs like this. Dave

 

[Jasonb]

Put the tool in the right way round for a start ;D if you plan to run the mill backwards watch out as that head screws onto the shank so will unscrew itself if used in reverse

If you clamp the bit of scrap about 4.3" away from the outer face of the cylinder with teh mill axis mid way between the two then take a few cuts until you have reached the required diameter. Don't touch teh boring head any more just advance the cylinder towards the cutter until you remove what you want, this won't affect the radius just how far the centre of teh boiler is from teh centre of teh cylinder.

One problem that I see is your cylinder bore may be too close to the top of the boiler to allow the crank to turn but I may be wrong.

 

[Tin Falcon]

Now I see said the blind man!!!! Pictures help so much .

measure the diameter of your boring head . looks like two inches will use that as an example.
center the moving par of the boring head. finger feel should get you within a few thousandths.
set your BB out 1 inch . you now have a 2 inch radius now turn your micrometer setting on your boring bar .214. and you have it.
Or set your tool out 1.2 inches then move your mic.14 . i think you get the idea.
you could turn a gage on the lathe from a piece of extra stock. .
Tin
and yes I was referring to hole size

 

[Tin Falcon]

Another option if your lathe swing is large enough is mount your cylinder on a face plate in the lathe counter balance with scrap and do it that way .
Tin

 

[firebird]

Hi

Thanks Dave and Tin. I'm getting the idea now.

So you spotted the deliberate mistake Jason Thm: Thm: I did say it was a quick mock up.

You are quite right about the cylinder being too close to the boiler, I was just drawing it up when it occurred to me as well. I'll have to build it up with a spacer piece.

Cheers

Rich

 

[Ken I]

Bolt two pieces of drilled barstock (scrap) to the table so the gap between them is ±4.4".
Guestimate the tool to the centre and set until it just touches both - you are now ar ±2.2" rad - adjust and take cuts until you measure 4.428" diameter cut between the two bosses.

2c

Ken

 

[MachineTom]

This is not that hard. Take an edge finder first and zero the edge of the vise, not clamping surface. now add boring head and bar. Crank off the radius distance, and set the contact with the vise edge and cutter, now the radius is ready to be cut.

 

[Groomengineering]

+1 on Toms method.

Cheers

Jeff

 

[firebird]

Thanks Jeff, Tom and Ken

Cheers

Rich