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davidh
08-06-2011, 11:39 AM
i am asked to chuck up each of 4 slides from motorcycle carbs so i can carefully shave off .007 from the lower end of each one. my concern is damage to the slide barrel from the chuck jaws.

i do not have any soft jaws but my thought is to wrap one layer of masking tape around the diameter to protect it. . . . and of course not reefin' on the wrench when i tighten it. . .

is there a bettr / easier way to do this ?

thanks in advance. . .

JoeFin
08-06-2011, 11:43 AM
Make some Aluminum soft jaws and true to a bore .001" less then that of the slides. Be sure to finish the soft jaw bore with 325 gt sand paper too

Here is a photo of a set of Al. soft jaws I made in about 3 hours when I was pretty new at machining. Notice the lip on the inside diameter of the soft jaws. I would recommend this same lip on the soft jaws you'll need for the carburetor slides.

http://i198.photobucket.com/albums/aa83/Freakindj/Lathe/jaws002.jpg

My thinking being Soft Jaws made of equal hardness material and bore to a close fit will better disperse the clamping pressure equally and less likely to distort the shape or mark the surface.

A.K. Boomer
08-06-2011, 11:53 AM
You should be fine with just what you stated --- one layer of tape - .007" is a cake walk and just take it in two passes with super sharp HSS --- most of the slides iv worked on were actually anodized so you might have an initial skin to break through but it also makes it tough for the jaws to jack with esp. with a thin layer of tape...

topct
08-06-2011, 12:05 PM
I would make a simple collet. A round piece of aluminum, bored to closely fit the slide, put a match mark on it so you can remount it in the 3 jaw in the same position. Then remove it from the chuck and saw a slot through one side of it.

winchman
08-06-2011, 12:06 PM
Know how delicate carburetor slides are and how sensitive they are to damage, I'd make a collet to hold them.

Why do they need to be shorter?

quadrod
08-06-2011, 12:09 PM
I use coke cans for protection from the jaws on soft materials. Can cut to size and good to go.

davidh
08-06-2011, 12:39 PM
Know how delicate carburetor slides are and how sensitive they are to damage, I'd make a collet to hold them.

Why do they need to be shorter?
The engine has a wild cam & bored .090 and the Honda folks said that plus a different needle set will allow it to actually idle. 78 honda 750 .

Thanks for the ideas . . .

Black_Moons
08-06-2011, 02:48 PM
I would make a simple collet. A round piece of aluminum, bored to closely fit the slide, put a match mark on it so you can remount it in the 3 jaw in the same position. Then remove it from the chuck and saw a slot through one side of it.

1+, love making my own mini collets. Chuck saws will clamp the collet closed. its so easy.

vpt
08-06-2011, 02:56 PM
I use coke cans for protection from the jaws on soft materials. Can cut to size and good to go.



Yes, I use pop cans all the time for all kinds of clamping situations. I finally just made a set of aluminum jaws for my vise a few weeks ago after wanting a set for years. I may make a set of soft jaws for the lathe some day. For carb slides I would look around for some plastic though. Maybe like a plastic soda bottle.

Just the other day I had to switch my jaws around multiple times to do the cuts needed on a part I was working on. About the third time I was unbolting the jaws I was thinking to myself how nice it would be to have extra chucks with different jaw setups just ready to go. Kind of like extra tool holders for the QCTP.

Peter.
08-06-2011, 03:26 PM
I use off-cuts of gasket paper. It's thick, pliant and doesn't slip when oily or wet.

John Stevenson
08-06-2011, 03:52 PM
Just the other day I had to switch my jaws around multiple times to do the cuts needed on a part I was working on. About the third time I was unbolting the jaws I was thinking to myself how nice it would be to have extra chucks with different jaw setups just ready to go. Kind of like extra tool holders for the QCTP.

Same here so I made these.

http://www.stevenson-engineers.co.uk/files/hexjaws1.jpg



http://www.stevenson-engineers.co.uk/files/hexjaws2.jpg

Simple enough.
Set of soft jaws machined with a tenon and three tapped counterbored holes in each all done at the same setting in the mill.

The new jaws are offcuts of mild steel hexagon with three slots in the back and a central hole and counterbored each end. One counterbore has a dowel loctited in.

So you get three choices of diameter depending on which tapped hole you choose and six positions of the new jaw, so in effect 18 positions and if you double bore the hexagons, as one has been in the first picture you can get even more life out of them.

I have a piece of card behind the lathe where I can record what number jaw and holes is applicable to what job.

MCS
08-06-2011, 03:53 PM
By turning a stepped fixture in the chuck to supprt and center the slide, and a plate with a centerhole, you can turn it between centers.

It won't go anywhere, no damage to the slide and repeatable length comes free.

Forrest Addy
08-06-2011, 04:25 PM
Never use stickum tape of any kind to protect work from chuck jaws. The adhesive is nothing more than a lubricant: the work WILL slip in the jaws with any kind of thrust at all. Protect the work with taps or strips of shoe box cardboard or file folder paper. If the work is stout enough, use copper. Thin wall stuff with a good ref dia should be soft jawed or potted.

I can't recall the details of the last motorcycle carb I saw but I know the sldes are delicate. I strongly suggest you make some pie jaws so you get a full circumference grip on the part. The hex jaws seen earlier work good too.

I gotta editorialize here. This is a situation where a three jaw really shines. Soft jaws bored to suit have the gentlest, most secure grip for delicate cylindrical parts unless you make a pot for them.

John Stevenson
08-06-2011, 04:36 PM
I used to make carburator slides [ God that sounds just like Evan ! ]
I'll see if any of the old jigs are still around and post them later if they are.

topct
08-06-2011, 05:13 PM
I used to make carburator slides [ God that sounds just like Evan ! ]
I'll see if any of the old jigs are still around and post them later if they are.

I was going to post a picture of the jig I made to re-sleeve Amal concentric slides. But I made it to hold them at the bottom of the slide. That's what he wanted to work on so it won't work.

MCS
08-06-2011, 05:16 PM
I used to make carburator slides [ God that sounds just like Evan ! ]
I'll see if any of the old jigs are still around and post them later if they are.

I have made complete carburators, without jigs.

But as you stated, only Evan can do these things, so I didn't.

darryl
08-06-2011, 08:53 PM
Glue two layers of 3/4 inch mdf together and mount on a faceplate. Bore for a close fit of the slides, leaving a lip at the bottom of the bore if required to keep the slide squarely bottomed. Drill three pilot holes evenly spaced about 3/8 inch from the edge of the bored hole. Insert slide, then a wood screw into each pilot hole. That will expand the mdf inwards just enough to grip the slide.

Yow Ling
08-06-2011, 09:05 PM
if you put the slide upside down you could bolt it to a piece of metal through the needle hole then use the mill to remove the 7 thou. Wouldnt even need to touch the sides