using parallel bars

A

alinwa

oft dis'd member
I've been using my adjustable parallel bars as height adjusters in my milling vise, to support flatstock for drilling. Then I saw a tutorial where the guy was using the parallels to transfer dimensions and to gauge inside dimensions...... am I "using my calipers as a crescent /wrench" here?....... Are sliding parallel bars stout enough for workpiece support or are they a setup and gaging tool only?

thanks
al
 
Al, I was taught to use them as a set up and measurung tool. I guess I have enough ground parallels to not need my adjustable parallels.
 
Al, I'm with Butch, get yourself a bunch of parallels. If I may suggest, go to a local sheet metal shop, have them shear you a progressive assortment of pairs, at least in 1/8" increments. My most used parallel pair is 3/16" shorter than the jaw. 1/16" thick stock will work, but .093" seems a little better. You will of course have to machine them yourself, a 1/2" four flute carbide buzzed up pretty good will leave a good finishing cut. They will be soft and will have to be handled carefully, but when you screw up at least they won't ruin your tooling. Save your heavy duty steel box banding straps, cut them to length and bend them to make springs to hold the parallels against the jaws.
Charlie
 
You are right Charlie. After you've had a shop for awhile you will accumulate quite a stock of parallels. It is easier for me as I have a surface grinder and can make a special pair if needed pretty quickly.
 
alinwa said:
Thanks guys ;) I'll get me a boxfull of parallels...... gimme an excuse to get some wavy's too.
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Disadvantage on the "wavy's" is you never know where the "wave" is and will surely drill a hole in the parallel. Which makes you unhappy at the least, but always costs you time.
Charlie
 
CharlieH said:
Disadvantage on the "wavy's" is you never know where the "wave" is and will surely drill a hole in the parallel. Which makes you unhappy at the least, but always costs you time.
Charlie
Click to expand...

This is so funny, and I'm sure it's true. It's why I haven't ever bought any wavy supports. But a couple times this week I wanted to drill tight to the edge on brackets.....I was all peeking in under and wasting time anyways! Measuring with my fingers....

Luckily for me this is a hobby at this point.

F'rinstance I decided I needed a dedicated DRO on my tailstock because my cobbled together temporary topmount was in the way. That was about 30mnhrs ago. Now I've got a great DRO mounted and set up, all shrouded and protected with an adjustable tensioning wheel so's it don't bounce, but if I was on time I coulda' just bought a better lathe!

LOL

al
 
I may be doing it wrong...

...but, after I set up the piece on the parallels and tighten the vise, I've always been able to slip the parallels out without too much effort. :confused:

Jim
 
Your vice jaws are cocking, which can get very exciting on occasion. In other words the jaws are angling a bit and lifting your work piece and not always uniformly. Little bit too much on a cut and the excitement begins. Really tough on carbide bits.
 
Try a dead blow hammer

blades said:
Your vice jaws are cocking, which can get very exciting on occasion. In other words the jaws are angling a bit and lifting your work piece and not always uniformly. Little bit too much on a cut and the excitement begins. Really tough on carbide bits.
Click to expand...

I find one gentle tap will firmly seat the workpiece against the parallels. No way can I get one out after that.

Rob Carnell
Sydney, Australia
 
Rob Carnell said:
I find one gentle tap will firmly seat the workpiece against the parallels. No way can I get one out after that.

Rob Carnell
Sydney, Australia
Click to expand...

Concur with that. After watching several videos where the operator gave a firm whack to the workpiece after the initial tightening, I tried it myself and it works great. If you can remove the parallels, the piece isn't being held right.
 
adamsgt said:
Concur with that. After watching several videos where the operator gave a firm whack to the workpiece after the initial tightening, I tried it myself and it works great. If you can remove the parallels, the piece isn't being held right.
Click to expand...

Gents,

That's how I was taught. Tighten the vise, and give the workpiece a whack. The parallels shouldn't move after that. If they do, the workpiece is not level.

In my travels, I have seen quite a few Bridgeport's with the manual feed wheel broken off. I've always suspected this was due to an errant hammer blow whilst tapping down the workpiece.

HSS tool bits work pretty good as parallels. I have some giganto-mondo one's that I use all the time. Dowel pins work good, too.

Justin
 
Something I haven't seen mentioned is the use of soft jaws as an alternative to parallels. In the shop we make a couple hundred sets of steel soft jaws at a time so that we have them on the shelf whenever needed. I designed the jaws so that they are completely symmetrical. Instead of using standard socket head screws, I use screws that are about half the head thickness so that I can put the counterbores on both sides of the jaws. The height of the jaws is figured so that the bolt holes are centered. These jaws can be flipped and reversed. Essentially four working edges per jaw.

You can mill steps in the jaws to simulate using parallels. I keep box sets of hardened parallels on hand in 1/8" increments. They work in most cases but when I have a unique clamping requirement I reach for a set of jaws that have a step in them or I mill a new step. I find this to be much faster than building and maintaining boxes of random sizes parallels.
 
Thanks to y'all, my visemanship is improving!

OK, another question, please share some thoughts on a hydraulic vise. If they do what I THINK they do, which is the jaws swivel to equalize force over the piece, then they seem a good thing.

Comments?
 
Al, I have a ? that is marked M600 hydra. I use it to hold irregular objects in the mill. It came with the tooling in my shop that I bought years ago. If I have an opportunity I can email a photo later.
 
alinwa said:
I've been using my adjustable parallel bars as height adjusters in my milling vise, to support flatstock for drilling. Then I saw a tutorial where the guy was using the parallels to transfer dimensions and to gauge inside dimensions...... am I "using my calipers as a crescent /wrench" here?....... Are sliding parallel bars stout enough for workpiece support or are they a setup and gaging tool only?

thanks
al
Click to expand...

A simple explanation about your "parallel bars" they are meant to be used as a measurement transfer tool and can be used for workpiece positioning. They are not designed to be a load bearing fixture in a machining process.
 
Thanks Jerry. They don't work very well anyways but I had them in hand.... I'll not apply pressure to them again.

Also, I see the wisdom of tapping the workpiece down and will not hammer on my sliding bars!

al
 
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