Small o.d. grinder job

mmcmdl said:
My bubble isn't bursted ! :big grin: If you sleep well charging $25 an hour , most likely you could sleep GREAT at $15 an hour . :grin:



Most individuals prefer to " work smart , and not hard " . One day you'll get old and won't feel like working " hard " . ;)

In the end , charge what the market commands , $15 or $250 . As far as the pins , someone whom has a small shop may grind them for $25 an hour , but ain't no way a machine shop will do anything at that price . Most have minimum charges also .

Also , those pins started out as A2 and now they are O2 ? :dunno: And $75 set-up and $10 a pin comes up to $195 in my book . How did you arrive at the $1111.83 total ? If it's the shipping that adds all that cost , we're ALL in the wrong business ! :bawling:
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I sleep just fine at $25 an hour and I'm sure my customers do too. You can't charge, what people don't have. That's a losing proposition.

I AM a machine shop and I do whatever the job requires for $25 a hour. The one quote said " $85 minimum lot charge" Means nothing to me as I work by the hour.. I guess if I paid that dude $3g to grind these pins I sell for $35 a piece, he can continue paying the mortgage in the mansion he lives in, but it ain't gonna happen.. I could never charge $350 for one of these pins, but I still need to pins to make a living, so I will do whatever it takes to make these pins and still be able to sell them for $35 a piece and make a profit.

The straight pins are O-1, the center pins I believe are 8620 and the small pin is A-2. (I machine and heat treat the straight and the small pins myself.) The center pins were made in the '60's , but all the pins are are about the same Rc hardness. The same grinding stone is used to grind all 3 different pins

I use to use O-1 on all of them, but A-2 is more wear resistant and doesn't have to be oil quenched (air hardening) before tempering, So I save a step which saves me time.

As for the $1118, that is for grinding all 3 sets of pins (see price chart above) and that doesn't even include return shipping, which I am 99.999% sure it would not be $8 in a small flat rate box from the Post Office like I would send them in. It would most likely be UPS and cost $30 or more (whatever they guy feels like charging at that particular time in his life)
 
Most individuals prefer to " work smart , and not hard " . One day you'll get old and won't feel like working " hard " .

I better have something stashed back for retirement then huh? . Getting old still don't give ya the right to steal from people. I plan to work til the day I die any way. I can rest then.
 
mmcmdl said:
I would suggest buying a Cylindrical grinder , moving it into your own space , and doing them yourself
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I have a cylindrical grinder and am wondering how you would accomplish that. Not trying to be smart or confrontational.
My cylindrical runs the part between two dead centers. So requires a drive dog. Would you run with a drive dog and then reverse the part? putting the drive dog on the other end. Doesn't seem like a good way.

I would probably run those on my surface grinder with a between centers fixture. I have one that is motorized but it also has dead centers and requires a drive dog.
I have a second between centers fixture that the center on the drive end does rotate with the part. and my thought was to use something like this and
hope the center would spin the pin for grinding. The only chance of that happening is if an abrasive of some kind was applied to the center that turns to make the pin spin with it.
That fixture is not presently motorized. I have motored it with a ball allen bit and a cordless drill. Not the neatest but saved some wear and tear on the fingers from turning the crank.
 
Mutt said:
The pins are less than 2" long and have 60º centers on either end. I have one dozen that need to be ground, Any one up for the job?
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Possible I could do that for you.
My between center fixtures for my surface grinder are accurate. I have built my own rifle chamber reamers.
My issue is how to turn and grind the entire pin. I usually have an area for the drive dog to attach to that spins the part.
Not sure results would be acceptable if grinding part of a pin and flipping to grind the other end.
 
I talked with a friend of mine that has a good sized CNC machine shop in Iowa. He says there are some companies that make and sell a driver, just like one used for a wood lathe. It has a few teeth that just sorta bite onto the end of the part and drive it. It doesn't have to have a true bite as there isn't much pressure on the part when grinding off .0005 or so. So, mr. Gray, what kind of shank does your drive end have? Maybe I can locate one of these drivers and get it for ya
 
Both that I have I believe are shop or school builds. I got them on ebay.
The one with the center that would turn with the work is the farthest away in the picture.
I got it with no tailstock center and had to build that. The "powered" (rotating) center is one piece with it's spindle.
I am familiar with the drive style you mention. It would take building another spindle to implement that on that fixture (I think?).
That was why I was thinking out loud wondering if an abrasive would be enough to make the part turn with the center.
Also the centers on that fixture are small. Wondering if they are large enough to fit your part centers.

Also thinking there may be a way to attach a spring loaded drive pin to the drive wheel on the dead center fixture (close one in pic).
It would have to be outside of the center taper since both are dead centers. So not sure if that would drive/work at all.
288587
 
rgray said:
I have a cylindrical grinder and am wondering how you would accomplish that. Not trying to be smart or confrontational.
My cylindrical runs the part between two dead centers. So requires a drive dog. Would you run with a drive dog and then reverse the part? putting the drive dog on the other end. Doesn't seem like a good way.
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That's exactly how to do it . Long or short , it's a shaft . Drive with a dog between centers and grind up to the dog , then flip and repeat . That grinder will hold .00005 with no problem . You'll need to adjust table to pull the taper out .
 
I'm picking up my SG on Monday . It would make short work of grinding those shafts . I don't have my converter any longer and it's going to take awhile to move that machine into the other place . Spose to hit 70 degrees here tomorrow so I'll be busy moving things up , and moving things down , but eventually , a small shop will be in existence back where I started . :)
 
mmcmdl said:
That's exactly how to do it . Long or short , it's a shaft . Drive with a dog between centers and grind up to the dog , then flip and repeat .
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So doing it on my cylindrical grinder would be the better way sounds like.
Narrowest wheel I have is 1"
Flipping the part and attaching the dog will take much longer than the grinding.
Would be much quicker than doing it on the surface grinder though.
 
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