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barts
04-08-2009, 01:54 AM
I need to clean up the 1.25" diameter, 5" deep bore for the piston valve on the 2.5" x 2.5" steam engine I'm rebuilding... and my 2" boring head doesn't look like it will be happy w/ a 1/2" diameter boring bar that long.

I thought about line boring it on the lathe, but can't figure out how to mount the cylinder on the cross slide w/ a lot of complications, and setting the protrusion of the toolbit seems awkward as well. I guess I could bolt the cylinder on the lathe faceplate, but that's a lot of cast iron winging around. ...

The simplest idea seems to be to get a bigger boring head so I could mount 3/4" boring bars.

Has anyone got a better idea? What do people thing of the cdco tools 3" boring head?

- Bart

Oldbrock
04-08-2009, 02:33 AM
Too bad you live so far South, I could hone it for you on my Sunnen hone. Find someone close to you who has one, should clean up in an hour or so. Peter

.RC.
04-08-2009, 02:59 AM
Mybe it is just me but I can never bore holes sucessfully with a boring head on a milling machine...All I get is constant chatter..

I would be setting it up on the lathe or getting it honed..

JCHannum
04-08-2009, 09:06 AM
When building a model John Deere engine, I was faced with the same problem. I made a sub table to replace the compound. I used a piece of 1" thick aluminum.
http://i320.photobucket.com/albums/nn351/jchannum/P1000216-1.jpg

I cribbed the casting in place and used hold downs to hold it in place. The rear of the engine would not premit line boring, so I made a very stout boring bar to hold the cutter.
http://i320.photobucket.com/albums/nn351/jchannum/P1000195.jpg

I had acquired this gage in my roamings, and it works very well for setting the cutter protrusion. For one time use, a similar gage could be made by clamping a depth mic to a V-block.
http://i320.photobucket.com/albums/nn351/jchannum/P1000222.jpg

Your Old Dog
04-08-2009, 09:12 AM
That's pretty slick JC.

Bill Pace
04-08-2009, 09:39 AM
You a clever devil, JC :D -- Slick set-up....

Glenn Wegman
04-08-2009, 10:21 AM
Same only different!

I use DeVlieg adjustable boring bars and have since this pic made a 12" X 18" X 1.250" thich alum bed plate. Luckily, it has a large T-slotted cross slide.

http://img.photobucket.com/albums/v647/Fighter1/P7300698.jpg

Glenn

Circlip
04-08-2009, 10:41 AM
For line boring same as JCH's setup but with a between centres (centers) boring bar made from 1" dia. material.

Regards Ian.

The old ones are the best ones :)

TGTool
04-08-2009, 11:05 AM
Same only different!

I use DeVlieg adjustable boring bars and have since this pic made a 12" X 18" X 1.250" thich alum bed plate. Luckily, it has a large T-slotted cross slide.

http://img.photobucket.com/albums/v647/Fighter1/P7300698.jpg

Glenn

Glenn,

That's a VERY interesting operation.

I'm even more intrigued by the drill chuck with S&D drill plugged into the top right corner. Could you tell me more about when and how I'd use that particular trick? :D

JCHannum
04-08-2009, 11:21 AM
Sometimes you have to stop in the middle of a job and make tooling or fixtures to complete it. It pays to take your time and make a fixture that will be useful in the future. That was the case with the sub base I made. I did take the time to drill & tap sufficient 3/8-16 holes for future use. It is expendable if need be, and other holes can be added as necessary. It has taken it's place with the rest of the lathe tooling and comes in handy from time to time.

Glenn's drill chuck appears to be in a bed turret, but that still is a very impressive set up.

Carld
04-08-2009, 11:42 AM
Bart, I have made several boring bars 1" diameter with a 1/2" shank to fit the boring head. I use brazed carbide cutter in the end of the bar. Some of them have the cutter at 90 deg and some have the cutter at 45 deg.

You can also make a bar with a pilot at the end and mount the work high enough to use the bar in a collet and do it like a line bore setup. You could hang the work off the side of the table. There are a lot of ways to do it on the mill.

I have bored holes with home made bars in boring heads and used the full travel of the quill and got a good surface finish. Test bore with some scrap if you can.

Glenn Wegman
04-08-2009, 11:57 AM
Yup, six station bed turret:)

Spin Doctor
04-08-2009, 12:05 PM
Same only different!

I use DeVlieg adjustable boring bars and have since this pic made a 12" X 18" X 1.250" thich alum bed plate. Luckily, it has a large T-slotted cross slide.

http://img.photobucket.com/albums/v647/Fighter1/P7300698.jpg

Glenn

Gee, I wonder what size and model radial you are working on there. Looks like you are repairing the magneto mounting area

barts
04-08-2009, 01:14 PM
Thanks folks; now I have some interesting ideas to mull over... I particularly like the idea of building a proper line-boring plate for the lathe, and that gage seems like the right approach. Seeing those pictures gives me some confidence that I can make this work.

I'll try making some tapered collars for the boring bar to center the cylinder casting during setup...

- Bart

Glenn Wegman
04-08-2009, 01:47 PM
You might want to snug your cross slide gibs up a little so the slide doesn't want to move in and out with the bar rotation if you plan on taking much of a cut, or have an interrupted cut when you start out. I zero'd my .0002" resolution DRO in X and it never even flickered during the cut. I did some fairly heavy cuts in steel one other time and the slide wanted to move back and forth a little, but I just zero'd it back up for the finish passes and it was fine.

Glenn

GadgetBuilder
04-08-2009, 02:16 PM
Gingery provides a design for a simple tool to adjust a between centers boring bar.

Picture here should make the description understandable:
http://www.gadgetbuilder.com/Main_Block.jpg

It is a little J shape strap that wraps around the boring bar and clamps the jig to the bar using a bolt; a second bolt is used to set the bit. Move the bolt against the cutter, back off by the incremental depth of cut (judged using a gap gauge), lock the bolt with the nut. Then loosen the cutter and advance it until it hits the end of the adjusting bolt. This works surprisingly well considering the simplicity and cost of the adjusting jig.


John

barts
04-22-2009, 11:26 PM
JCHannum, thanks for the good advice. I got that plate done and the valve bored out:

http://i564.photobucket.com/albums/ss85/KernelSander/dsc_7993.jpg

Worked like a charm; cleared out about .035 before everything was clean.
http://i564.photobucket.com/albums/ss85/KernelSander/DSC_7990.jpg

Made the plate, boring bar, machinist's jacks, etc.... you can just see the tapered collar I used to align the cylinder before clamping next to the chuck.

- Bart

JCHannum
04-23-2009, 12:09 AM
Sometimes what seems to be the most complex solution is the simplest. Once the tooling has been made and the job accomplished, it is always available for the next time.

Looks like a nicely done job and a good solid set up. I am interested in the engine, what is it powering? Please show us the completed project.

Scishopguy
04-23-2009, 04:40 PM
I had acquired this gage in my roamings, and it works very well for setting the cutter protrusion. For one time use, a similar gage could be made by clamping a depth mic to a V-block.
http://i320.photobucket.com/albums/nn351/jchannum/P1000222.jpg[/QUOTE]

Jim...I just bought one of these gages this past weekend at the flea market in St. Pete. I didn't know exactly what it was for but I knew it was some sort of fixture for measuring depth on a cylindrical part. It came with the vee block micrometer, 3 question mark shaped clamps, and a nice wooden case to store them. The guy at the booth didn't have any idea what it was and I got the set for $5. I wish I coule get my photobucket account to work so I could show off a photo of it and some other treasure I acquired. :( My problem is I am on dial up and I have not gotten the upload to work. One of these days I will figure it out and be able to show and tell like everyone else.

JCHannum
04-23-2009, 06:28 PM
I too have dial-up and use Photobucket. It is simple enough even for me to use.

I acquired the gage with a bunch of stuff and didn't know what it had been made for until I made up the boring bar for that project and began to try to figure out how I was going to measure the cutter protrusion. It then took my rooting around in all the boxes of things I have that are too good to throw away, but of no known use to find it.