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darryl
09-28-2015, 01:12 AM
I'm sure we've all had tense moments- times when you're about to do something and nervous about the outcome- like plugging in the machine you've just rewired and hoping it doesn't put on a free smoke show.

Had one of mine today- not anything unusual, but I was working on my saw blade arbor and the time came to shrink fit a flange. Shaft is 5/8 and I bored the flange to .620 by my dial gauge. This should mean the bore is .622 for a 3 thou interference fit- a bit tight possibly? Anyway, I heated the flange til it turned purple, then checked with a scrap of the same shaft I used for the arbor. The shaft went in a bit but seemed too tight so I yanked it out right away. Thought I'd better cool it off and check the bored hole to see if it was the same diameter on both sides of the part. Far as I could tell it was, so this time I heated the flange to almost glowing, then quickly placed it over the arbor. It slipped on easily and I rotated it in place to help it align. I don't think I had two full seconds before it gripped and couldn't be moved. Bit of a pucker factor there-

jhe.1973
09-28-2015, 02:10 AM
Reminds me of when I was a tool & die maker for West Bend Co. (cookware). They used to draw the aluminum blanks over a punch into a tool steel die.

IIRC, these dies were often about 16 - 22 inches in diameter and about 3 - 6 inches thick. To save the cost of making them entirely from tool steel the outside four inches or so was a mild steel ring that was shrunk on.

It was a two man job w/both toolmakers using oxy/acet rosebuds and just as with your project, you only had the one chance to get it right.

They already had a system worked out by the time I came to work there and I only had to do it once, so I can't remember just how we had everything ready to drop the hot & heavy ring over the tool steel die.

Anyhow, it was a two man pucker factor!

bborr01
09-28-2015, 08:17 AM
Daryl,

I don't understand the part about boring to .620 so it is .622.

Also, even at .622, you have way too much press on it.

Brian

A.K. Boomer
09-28-2015, 09:19 AM
I went too tight on a ford F-450 tranny main bearing sleeve I built,,, the saving grace was that the trans was aluminum and the sleeve steel - so it's just a matter of pouring more heat to it even once it does get stuck...

but it took allot of heat and me and my bro to press it in,,,

we joke that sometime in the winter on a -20 degree day we will be walking by the truck and hear a "boof"
and either the sleeve and outer main bearing will turn to powder or the tranny case will be split in half...

one thing for sure - that outer main will never ever spin in it's bore again - the reason the beast had to come down in the first place...

jasnooks
09-28-2015, 12:01 PM
My buddy at work had this setup last week. He didn't seem to nervous, but i was waiting for it to flip over. That's a lot of steel hanging off to the side. And, no the Bridgeport isn't bolted to the floor.

http://images.tapatalk-cdn.com/15/09/28/10dabc3d9cfe0707cf42b134423ae26f.jpg

A.K. Boomer
09-28-2015, 12:08 PM
I bet that old power feed was barking at him a bit lol

flylo
09-28-2015, 12:36 PM
Is the yellow stripe on the mill the tip over mark?

rklopp
09-28-2015, 12:43 PM
My buddy at work had this setup last week. He didn't seem to nervous, but i was waiting for it to flip over. That's a lot of steel hanging off to the side. And, no the Bridgeport isn't bolted to the floor.


Good grief, look at that monstrous endmill in a poor R-8 spindle! Tell me that didn't chatter ten ways to Tuesday. Is this a pro shop?

George Bulliss
09-28-2015, 12:47 PM
Done similar plenty of times without a problem. You won't rough with it, but for finishing a pocket wall (a few thou.) it works.

spongerich
09-28-2015, 02:00 PM
I'm sure we've all had tense moments- times when you're about to do something and nervous about the outcome- like plugging in the machine you've just rewired and hoping it doesn't put on a free smoke show.

I always grab a fire extinguisher and keep it right next to me whenever I plug in a new machine or one that's had wiring work recently done.

Haven't needed it yet, but my shop is in my 100 year old barn, so I'm like The Scarecrow when it comes to the possibility of fire. I have fire extinguishers mounted all over the shop, but I like to have one right there whenever I think there's a possibility I might need it. Maybe I should get a little one and make a belt hook for it :cool:

PStechPaul
09-28-2015, 03:28 PM
Drink lots of water and make sure the zipper on your fly works quick and easy.

On second thought, for an electrical fire, maybe not so much!

A good fused disconnect is good to have in case things go awry. The large handle is easier to operate than a circuit breaker, and the steel enclosure provides better protection.

flylo
09-28-2015, 04:03 PM
Worsed I've had is the forklift LP diaphram went bad & as propane goes down it filled the engine & when I hit the key it didn't start so I opened the hood hit the key & the distributor cap jumped & 1/2 the shop lit up with 3' high flames about a 40' square, burned all the hair off my legs, as started several thing on fire. Thank God I had 2 extinquishers close by. Now I turn off the tank even it's only off 5 minutes. I had to put the dist cap back on but no other damage except the fire ext mess.

danlb
09-28-2015, 04:15 PM
Those tense moments happen frequently around my shop. I shift from one hobby to the next as the mood hits. A few tense moments that come to mind...

I check everything over and over each time I light up my little Oxy - Propane brazing torch. One valve opens clockwise, the other counter clockwise. I can't help but imagine what will happen when I turn the wrong one the wrong way and cause it to burn back into the hoses.

Every time I open the valve on the 2300 PSI argon tank for welding I recall the cautions about keeping your hand away from the top of the valve... Just in case the valve blows out and shoots through the roof.

Some tools are used infrequently, so they tend to have the higher pucker factor. The longer between uses, the better chance that you forget to do something right. My woodworking tools fall in that category. When I chuck a block of wood (in my wood lathe) I always feel anxious for the first minute while it's out of balance. Then there's the table saws and skill saws and routers. All of them are spinning sharp things wicked fast.

Electrical hookups are much less exciting. I have the tools to check the connections, so I virtually never have a concern about an electrical fire from mis-wiring.

Dan

dneufell
09-28-2015, 05:49 PM
Hey Flylo.....

That was real funny.....as the kids say lol

Dean

toolmaker76
09-28-2015, 09:31 PM
In the 80's I did wire edm on some mold cavity parts that were made by a special process. The raw material was worth $30,000 before I ever touched it, and they had a finished surface that could NOT be scratched or damaged, but it was the reference point for everything else, which resembled a rough casting.

Everything had a VERY tight tolerance. Multiple cuts, each of which had to be right. A thousand ways to mess it up. First few I did were successful, so then the customer asked for me by name. Never scrapped any of them, but I would stress over them to the point that my stomach hurt and my nerves were shot.

I left that company 25 years ago, definitely did not miss those parts, and don't think I've ever done anything as stressful since!

ironmonger
09-28-2015, 11:35 PM
<<snip>>

I check everything over and over each time I light up my little Oxy - Propane brazing torch. One valve opens clockwise, the other counter clockwise. I can't help but imagine what will happen when I turn the wrong one the wrong way and cause it to burn back into the hoses.

<<snip>>
Dan[/QUOTE]

I saw this demo at the FABTEC show in Chicago a few years ago.

https://youtu.be/pWe84DyPIsg

They made a believer out of me. I was kind of cavalier regarding there use before the demo... not any more

jasnooks
09-28-2015, 11:57 PM
I bet that old power feed was barking at him a bit lol
Power feed doesn't work, manual feed only. And from what he said, it was a bear to crank.

jasnooks
09-28-2015, 11:59 PM
Is the yellow stripe on the mill the tip over mark?
No, that's just marking the center of table travel. I'm not sure where the tip over mark is, luckily he never got that far

jasnooks
09-29-2015, 12:06 AM
Good grief, look at that monstrous endmill in a poor R-8 spindle! Tell me that didn't chatter ten ways to Tuesday. Is this a pro shop?
1" dia, about 4" long. He was just opening up a slot, making clearance for hydraulic lines. Nothing fussy, but yeah there was quite a bit of barking going on, lol.
Yes, it's a pro shop, and no, this isn't the norm for our place, but sometimes we have to do whatever it takes to get the job done.

boslab
09-29-2015, 04:35 AM
With respect to the original post regarding shrink fitting, once you heat a lump of metal and it shrinks it's final size is less than the size it was before heating (provided you exceed certain pints on the equilibrium diagram for that alloy, steel being an alloy)
This rather irritating or useful fact was known way back, wrought iron is particularly susceptible to permanent shrink and was as far as I can find used as a 'fix' for over length things and oversize things, I found it's earliest reference in an old book called a practical treatise on heat by I think Thomas black, it described getting cylinder rods, cannon bores and things to fit if they were oversize by heat quench cycles, I didn't beleive it but after a bit of experimenting found it was true, there's not a lot of permanent shrink per cycle but it is there, just an interesting thing it thought.
Looking at the mill with the giant cutter amusing, might need a bigger one, mill that is, what do pilots say, pushing the envelope ( I didn't know you delivered mail I said to my mate, a pilot, he weren't impressed)
Big lumps of expensive tool steel must be scary, I've heard tales, but to be honest I've seen big car press tools with loads of mods by way of plugs and inserts so I suppose nothing is irretrievable, tig welding certainly helped fix one or two dies I was involved with!
I saw some giant double helix gears, about 10' diameter on a scrap pile, reason unknown but the teeth were only half formed, someone blundered as they say, teeth to the left of me teeth to the right and none right!
I'm glad I only do rough stuff for myself, no stress
Mark

brian Rupnow
09-29-2015, 11:57 AM
Tense times indeed!! I have built many small/model gas engines, and since the desk in my design office is so conveniently placed just outside my machine shop door, it had often been my "test bench" for first start up of these small engines. Not anymore! Story involves an engine that wouldn't start when everything said it should, a severely flooded engine, and spark testing a sparkplug by unscrewing it from the cylinder head and laying it on the engine block to check for spark when turning the engine over. It HAD spark--Lots OF SPARK. Thank God for handily placed fire extinguishers and quick reflexes. Now I do my start up testing out in the main garage, away from all things flammable!!!

bborr01
09-29-2015, 08:02 PM
This didn't happen in my shop but in a close friends shop. He is pretty safety concious but sometimes things slip by.

He has a car hoist and does a fair amount of car repairs for friends and family. When he does brake work he would put the oil drain catch cart under and wash away with brake clean.

One day he was welding on an exhaust system and the oil drain cart was too close. He told me that in about a second flat he had about 8 gallons of drain oil all over the floor. The flames went out almost instantly but he had a real mess to clean up.

Brian