I Almost Choked!!

I’m tearing that hand powered grinder apart and am of course finding a bunch of issues but after I cleaned all the dirt and grime off the handle I found the name of the outfit that made it.

IMG_20191102_225355

 

So I jumped on FleaBay to see if there were any parts available and found this,

s-l1600 (1)

Vintage Goodell Pratt Toolsmith 485 Bench Grinder 22:1 Ratio * Scarce Item!!

Condition:
Used
Price:
US $249.00     <<<<<<<<<——!!!!
Longtime member
Delivery in 3-4 days
No returns
ARE YOU FUCKING KIDDING ME?!!!
Holy jumping Jehosephat.
Right off the bat I see that the one I bought is a slightly different model, it doesn’t have that clamping bracket and screw on it and there is no cover over the main gear. One of the tines for the guard adjustment bracket is broke off and the shaft that the main gear spins on has a bunch of wear on it.
IMG_20191103_131232
IMG_20191103_131141
After scraping about a half a cup full of crap off of it and taking as much of it apart as I could, I couldn’t get the main gear off the shaft because of the casting for the driven gear.
I studied it for a few minutes, stuck it in my Home Made Hydraulic Bench Press and pressed it right out.
One look and I thinks to myself that it isn’t anything special, it looks like plain old 1/2 inch steel rod.
HMM.
let me see, rummage rummage, move some shit and AHA!
I thought so.
IMG_20191103_131303
So now I need to cut me a little hunk off the end of that, drill a hole in one end for the retaining pin, round the ends off a little bit and press it back together. AFTER I clean everything up and paint it.
That broken tine is going to be an issue. I’m thinking that if I can find a suitable piece to use, of drilling, pinning and brazing something back on there.
Should be easy enough to get it cleaned up and at least operational again.
Two hundred and fifty bucks my achin’ ass, that is exactly what I was talking about yesterday at that garage sale thing where I bought this little unit for twenty bucks at.
Put the word Vintage in front of it and try and get some ridiculous price for it.
When I get done with this one it should be worth at least twenty five.

 

8 thoughts on “I Almost Choked!!

  1. After you make the shaft, measure it carefully. Then before you press it in place, heat the gear in the oven to about 350 and freeze the shaft as cold as your freezer will get it. It’ll press easier and you will be less likely to crack the cast gear.

    Guess how I learned this.

    Liked by 1 person

    • RE: freezing stuff to get it to fit. Home freezers rarely will go below -5 or -10F. Industrial chemical freezers will go to -130F. N2 (nitrogen) cryo pumps use liquid N2 at -275 to -290 F (liquid N2 is -323F). Dry ice is about -110F.

      Dry ice is a couple bucks at the local supermarket; if you have access to a dewar flask a gallon of N2 is about ten bucks but good luck finding a convenent local source of N2 unless you work in a chem lab (or know someone who does….).

      More than once I’ve used dry ice and a toaster oven from Goodwill to turn a difficult interference (press) fit into a “slip and shrink” fit. Pro Tip: heat gradually and slowly, ramping the temps up 20-30 degrees at a time, and clean all the oil off before heating; it takes time for some parts to heat all the way through. FYI, dry ice is compressed CO2 and it turns into gas as it warms; that outgassing will pressurize whatever you have it in. Use insulated gloves, the proper safety gear and do as much planning in the “dry fit” stage as possible because once parts hit room temp you have to move quickly. FYI, don’t forget that the heated parts may be 500F so watch what you set them on or let come into contact with them.

      Liked by 1 person

      • I have easy access to liquid Argon at work, Nitrogen if I really need it.
        The Argon comes out at -145 Degrees.
        It’s funny that you mention the CO2 expanding as it heats, that is exactly what they use the Argon for there. The parts are loaded into a containment vessel with a furnace covering them like an upside down coffee can. They evacuate it it by vacuum then start pumping the Argon in and applying heat. That makes the gas expand. At what they call “Hold” temperature and pressure, the parts inside can be over 2,000 degrees and the pressure inside can be as high as 30,000 psi.
        The pressure “squeezes” the impurities out of the softened metal parts and it also compresses the metal to make it tougher and stronger.
        The process is called Hot Isostatic Pressing.
        HIP for short.
        It’s my job to keep all that shit running.
        As for this little shaft, it isn’t pressed in real hard because it is pressed into Cast Iron. Too tight of a fit and it would crack or split it in the first place.
        It slid right out with minimal force using my little hydraulic press and I will probably be able to just tap it back in with a brass hammer or drift.
        If not the little press will make short work of it without much in the way of thermal differences

        Like

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