Dempster 6ft No 12 rebuild

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windybob
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Location: Ames Oklahoma

Re: Dempster 6ft No 12 rebuild

Post by windybob »

Looks like it's almost there. The outer bearing race is flush with the front of the snout. that's whats holding you up. not that there's a ridge there, but because everything is rusty, dirty, etc. The pinion gear that's left on the shaft will go through the snout, but only if the front race comes out with the bearing. Don't know how much penetrating oil you used, but it looks pretty dry to me. Hammer the race back in, oil everything up real good and pull it again. You will see what the resistance is when it comes out.
Call Dan Benjamin for parts. P M me for the phone number.
Windcatcher530 Dan
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Joined: Sun Mar 28, 2021 4:06 pm
Location: Alcove N.Y.i buy and restore

Re: Dempster 6ft No 12 rebuild

Post by Windcatcher530 Dan »

Larry that is great that your son has a interest in your project.. Your a lucky man.
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windybob
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Location: Ames Oklahoma

Re: Dempster 6ft No 12 rebuild

Post by windybob »

Being as I can see the future, and I know it will be out of the case, ( LOL) I will say how I deal with the mainshaft. First thing, is everything is going to be probably rusted together, so soak everything. Of course, the hub will go to the back, or the shaft will come out the front, to deal with the key. Once the key is visible, take it out, and the hub will be free. from the back or end of the mainshaft, you have the castle nut, maybe a whasher, a pinion, a pinion square key, a tube spacer, a bearing, #1751 another tube spacer, another pinion and square key, from here up you have the old style. There is the oil spiral, with 2 pins holding it to the shaft, a pretty stout spring, and a force-fit washer that you can heat and swell, and take off. The spring is LOADED so be careful. Measure and mark things, as they may go back and be used again. In front of the force-fit washer you have a bearing, #1751 again, with either 1729 or 1779 outer race, and then this is where I must speculate, because it's normall where the felt washer oil seal would go in front of a tin plate. the felt would be a different front "noseplate" than the one you have. You have the later front plate that holds the full-circle oil seal ( late model). The seal seals on the bushing which (yes it does) slides on the mainshaft. ( no key) This oil seal bushing has a chamfer on the rear side. Also on the inside of it, there is a groove for a oil sealing O-ring. These items are not for the older style, they are the newer style oil seal.

YOUR bearings may be 1751, but I think 1951 is the right number. For some reason, I can't remember.

The problem you are having is that you are pulling against the stout spring on the mainshaft, so instead of a rigid pull, you are dealing with a spongy pull. The oil spiral, stout spring, and force fit washer are uaually not used with the late oil seal. They are replaced by a longer oil spiral, that is as long as the spiral, the spring, and force washer.

The reasons for all this info will be clear later. Everything on a Dempster mainshaft should touch the other items on the mainshaft. There are 2 endplays when you reassemble, we'll get to that later.

When you ge it all out and take it all apart, put it in a vice and heat the force fit washer, it will slide forward . Then you can grind the 2 pins and punch them out and release the oil spiral carrier.

Notes....
You cannot buy a 1751 bearing anymore. It is a 1779 or a 1729 I forgot. The outer race is still the same number ( 1779 or 1729) Might be an X on the race number. Fine.
Don't toss the your 1751 (1951?) bearings, you will need a piece off them.
There is BABBITT on the top of the crank gear pedastal. Don't mess with it, it stays. If you take the case to a shop for cleaning, tell them to not mess with it. It is poured -in -place. Not an insert.
You can get any part you want for this head.
6 ft Dempster pinion gears can pass through the snout. 8 ft Dempster pinions NOT.
The full circle oil seal is CR # or National # 472354 ... new bearings are 1779. new races are X1729.
Dempster mainshaft is NOT 1 INCH. it is 15/16. Crosshead shaft is 3/4 cold roll. Pumprod that come out the bottom of the neckpipe is 1/2 inch cold roll.
Call Dan Benjamin for parts. P M me for the phone number.
Windcatcher530 Dan
Posts: 1901
Joined: Sun Mar 28, 2021 4:06 pm
Location: Alcove N.Y.i buy and restore

Re: Dempster 6ft No 12 rebuild

Post by Windcatcher530 Dan »

Bob you should write a book on repairing Dempster's. Seriously
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windybob
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Location: Ames Oklahoma

Re: Dempster 6ft No 12 rebuild

Post by windybob »

Ha! I already have. It's on this website in pieces and sections.
Call Dan Benjamin for parts. P M me for the phone number.
fiegland
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Joined: Mon Jun 27, 2022 2:09 pm
Location: Erie, CO

Re: Dempster 6ft No 12 rebuild

Post by fiegland »

Success! I was able to remove the main shaft. I drilled a small hole into the key in the hub and then tapped a few threads in it. Then I screwed a sheet metal screw into the key. I was able to pull the key out with a hammer claw on that screw. Then, I used a piece of wood to wedge into the hub and drove the hub off with a sledge hammer. I then build a jig with some all-thread. I was able to use the power of nuts and bolts to pull the race and main bearing out. Once it came out, the main spring shot out like a cannon. Luckily, my jig was bolted to the main case or else everything would have shot everywhere. The rest disassembled easily after that. For now, the only thing that broke in the disassembly was a few cotter pins. Now time to clean everything!
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CTXmiller
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Location: Waco, TX

Re: Dempster 6ft No 12 rebuild

Post by CTXmiller »

Nice work/progress.
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windybob
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Location: Ames Oklahoma

Re: Dempster 6ft No 12 rebuild

Post by windybob »

Great job! Thinking outside of the box at its best! I have no idea what that threaded part is to the left of the spring...
Call Dan Benjamin for parts. P M me for the phone number.
mtblah
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Joined: Thu Mar 26, 2020 12:09 pm
Location: new braunfels TX

Re: Dempster 6ft No 12 rebuild

Post by mtblah »

Larry , you will have the spinner up and running in no time at all , great to have younger generation interested ,
both of you learning at the same time ! Fun project ....
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