bad vibrations

[zeeprogrammer]

Near disaster tonight.

I was squaring a rectangular block of brass with the mill.
Had it up on parallel bars in the vise.
When I started, the parallels were not near the end of the piece.
The vibration moved one of the parallels out far enough for the end mill to catch.
The parallel shot out...at an angle...and got stuck.

The pic is a recreation...but this is how it ended up.

If the parallel hadn't hung up, and if someone had been eyeballing from that side...they might've lost an eye.

Otherwise...no real damage other than a small benign ding on the parallel.
Still, I'm happy I had my TP handy.

Point? Those parallels are loose when used to hold a part up in the vise. Take care to make sure they won't move. Other threads have used a packing peanut. [Edit: I had included 'a rag' but it was pointed out that the end mill could grab this. When I worked the second part...I used a balled up piece of paper towel. Hopefully this is sufficient to hold the parallel bars but soft enough to rip up should something grab it.]

I'm sure the more knowledgeable ones on this forum will have additional ideas.

 

[vlmarshall]

Sorry to hear about your chewed-up parallel, but at least it wasn't worse. Be sure to stone the burrs off of the top surface before you use them again.
Tapping your parts down with a dead-blow soft-face mallet, after you've clamped them, will insure that the part is truly flat, and will keep the parallel from sneaking away.
A spring or two between the parallels will also help keep chups out from under them while you're switching parts... I have a bunch of assorted springs for the job, and for tiny parts, where the parallels are too close together for a coil spring, a 6" length of steel banding material, bent into a cheap leaf-spring does the trick.

 

[Foozer]

Near disaster tonight.

I was squaring a rectangular block of brass with the mill.
Had it up on parallel bars in the vise.
When I started, the parallels were not near the end of the piece.
The vibration moved one of the parallels out far enough for the end mill to catch.
The parallel shot out...at an angle...and got stuck.

The pic is a recreation...but this is how it ended up.

If the parallel hadn't hung up, and if someone had been eyeballing from that side...they might've lost an eye.

Otherwise...no real damage other than a small benign ding on the parallel.
Still, I'm happy I had my TP handy.

Point? Those parallels are loose when used to hold a part up in the vise. Take care to make sure they won't move. Other threads have used a packing peanut or a rag.

I know its not funny, but having had things take on a life of their own at times. . . Yup tap the part down, something as mentioned in previous reply to give them resistance to movement, But no RAGS please. Catch a rag and it catches something else and before you can say S@%T, you got blood spatters on the wall, well maybe not that bad, but you don't want to test it either.

Not ragging on ya (pun) don't want ya to get hurt over a buck or two of stock.

 

[zeeprogrammer]

vlmarshall: Thanks. I checked the parallel. Funny. I can feel the ding...but I can't tell if it's a burr or a dent. I checked with a magnifying glass. It's both. I'll do as you suggest with a stone (but lightly).

Foozer: Thanks. I edited my post to protect the innocent.

However...I'm not convinced yet (not having done it) that tapping the part down is sufficient, or that there's enough room to do it. At a minimum, should probably add a check to see how loose the parallels are. I held the part down against the parallels while I tightened the vise. Two problems I can see are 1) depending on the thickness of the part...tightening the vise too much could bow the part...effectively lifting it off the parallel bars and 2) the part can be so small that an insufficient amount of force is applied to the bars to prevent them from moving. So a more direct approach may be required.

Of course...there shouldn't be that much vibration in the first place.

I like the peanut idea...less likely to move around. Metal things like springs...might they move too? Is a balled up paper towel okay?

 

[Foozer]

vlmarshall: Thanks. I checked the parallel. Funny. I can feel the ding...but I can't tell if it's a burr or a dent. I checked with a magnifying glass. It's both. I'll do as you suggest with a stone (but lightly).

Foozer: Thanks. I edited my post to protect the innocent.

However...I'm not convinced yet (not having done it) that tapping the part down is sufficient, or that there's enough room to do it. At a minimum, should probably add a check to see how loose the parallels are. I held the part down against the parallels while I tightened the vise. Two problems I can see are 1) depending on the thickness of the part...tightening the vise too much could bow the part...effectively lifting it off the parallel bars and 2) the part can be so small that an insufficient amount of force is applied to the bars to prevent them from moving. So a more direct approach may be required.

Of course...there shouldn't be that much vibration in the first place.

I like the peanut idea...less likely to move around. Metal things like springs...might they move too? Is a balled up paper towel okay?

Actually got me on this one. Times I use tool stock as parallels in the drill press. I snug down the vise, tap the part down, check the parallels if loose tap the part again. If they be movement free I'll go ahead and do whatever it is I'm doing on the press. Always stop and check them as I go, if they seem to be coming loose, I slip em out. And your right about over torquing the vise, I kinda go for the "One eye tight" set. Guess its a feel developed from using torque wrenches over the years, you just get a feel for what the situation calls for, as you said in another post, to much tight and bolt get broken, we've all done it. I still do

 

[Maryak]

The smokers machine shop assistant is cigarette paper. Oz measure 0.00025".

Put one on top of the parallels at each corner with a bit hanging out to grab hold of push the work piece down as hard as you can and tighten the vise. Test each fag wrapper and see if you can pull it. The ones that can be moved are where you apply blunt force, (belt it with a dead blow hide hammer), until all papers are firm. The piece is now parallel to the vise base.

Hope this Helps. ??? ???

Best Regards
Bob

 

[zeeprogrammer]

Oh man. After 37 years of smoking...I quit last June.
The family will kill me if they see papers around here. ;D

That reminds me...I kept my last cigarette. Thinking was to smoke it after one year. Two more days to go.

People tell me it will either flash in my face (dry) or taste like dead bugs.

If any of you are smokers...please try to quit.

Sorry. The topic is home machining. 0.00025" huh? Someone here is a very serious machinist. Being from Missouri...I want to test that...now if I had some papers...

 

[deere_x475guy]

Zee, I keep some of the metal banding that they use to strap stuff to pallets for shipping. I works great and last forever. I always tap the part down firm on top of the parallels and try to push them with my finger to see if they are tight. If I remember tomorrow I will take a pic and post for you.

 

[Foozer]

If any of you are smokers...please try to quit.

'bout every day I try that, as soon as cranky sets in, smokes appear.

Sorry. The topic is home machining. 0.00025" huh? Someone here is a very serious machinist. Being from Missouri...I want to test that...now if I had some papers...

Use that paper trick to bring the cutting bit up to the stock, paper just tears and its close. Much better than the OOPS gouge doing it by eye brings

 

[DavesWimshurst]

Bob,
0.00025" That's thin! My pack of cigarette papers measures closer to 0.001 inch. But then I don't smoke though sometimes my tool bits do :big:
Dave

 

[Tin Falcon]

The smokers machine shop assistant is cigarette paper. Oz measure 0.00025".

Put one on top of the parallels at each corner with a bit hanging out to grab hold of push the work piece down as hard as you can and tighten the vise. Test each fag wrapper and see if you can pull it. The ones that can be moved are where you apply blunt force, (belt it with a dead blow hide hammer), until all papers are firm. The piece is now parallel to the vise base.

Hope this Helps. Huh? Huh?

Best Regards
Bob

Z:
Bob gives the basics very well there I was taught the same thing in tech school except with regular note paper
Another suggestion is put another piece of stock the same width as your work piece at the other end of the vice. vices do not like to grip well with the piece just at one end they work better if forces are even.
Double sided tape on the parallels can also hold them in place but still learn and use the method bob explained.
Be safe
Tin

 

[zeeprogrammer]

Thanks all.

Tin: And here I have two pieces of the same width anyway.

 

[georgeseal]

Guys,
In the BBS (big box stores) they have a section for insulating doors & windows

here you will find what is called backer rod. foam rubber in all kinds of diameters

you can use this stuff for all kinds of things. put a couple between parallels to keep them up tight to the vise. Put them in your chucks
to keep chips out

I almost forgot they can be used (if you cant find any other use) as insulation

 

[Maryak]

Bob,
0.00025" That's thin! My pack of cigarette papers measures closer to 0.001 inch. But then I don't smoke though sometimes my tool bits do :big:
Dave

To right it's thin

The thick correspondent left out a 1 : should be 0.00125"

Seem like the appropriate thread in which to make a

Best Regards
Bob

 

[tel]

The Tally Ho's (cig papers to you aliens ) are a great resource to have on mill, lathe or shaper. A damp one (lick it) applied to the top of a workpiece is a great tool for getting the tip of an end mill down to where you know where it is in relation to the job - just sneak down on it til the bit whips the paper away.

 

[zeeprogrammer]

- just sneak down on it til the bit whips the paper away.

Aha! That was the piece I was missing. I had seen a few places where they talked about using paper to tell where the bit was in relationship to the piece...but they never mentioned the bit was turning (or I just missed that part in my impatience to cut).

Any chance of a paper cut when it whips out? :big:

 

[BAH101]

I cannot remember where i say it, could have been on this forum, but someone use a styrofoam peanut (the type used for shipping) to hole the parrallels in place. Finally a good use for those.
Bryan