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  #11  
Old 05-23-2017, 07:55 PM
crystallographic crystallographic is online now
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Default Campbell 2536-6 nibbling machine rebuild Part 3

The business end of the main shaft is two pieces, with the shaft end counter-bored to receive the eccentric insert, which is adjustable.
P1010397 copy.jpg
The eccentric can be advanced for a longer stroke or retarded for a shorter stroke. These 3 strokes, combined with the two sheave speeds and the collet height adjustment, allows for metals from .025 to .250 to be nibbled smoothly.
P1030728 copy.jpg
The plunger bearing is bronze with a lengthwise split at 10:00, and is pinned in place. Another (bronze) pin with flats on one end keeps the plunger aligned while it reciprocates.
P1010398 copy.jpg
P1010402 copy.jpg
P1010408 copy.jpg
Shims allow for compression on the bearing.
P1010409 copy.jpg
The hollow cap screw retains the plunger alignment pin.
P1010411 copy.jpg
The fork engages the collet end, while the threads raise and lower the collet.

Up on top, the hand knob raises and lowers the collet in increments determined by the detents - IF the spring is awake and ready. Some penetrant awakened the spring, which took the dentent cap with it. Both were located nearby.
P1010405 copy.jpg
Detent cap up proud with a new spring and lube in the spring bore.
P1030722 copy.jpg
P1010404 copy.jpg

- end of Part 3 -
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Last edited by crystallographic; 05-23-2017 at 08:00 PM.
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  #12  
Old 05-23-2017, 08:35 PM
Michael Moore Michael Moore is offline
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Kent, can you use this 3/8" round wool felt from McMaster?

https://www.mcmaster.com/#8767k24/=17raqlt

I'd be interested in seeing some comments on the pros and cons of the Scotch yoke vs connecting rod for a home shop reciprocating machine if anyone wants to share them. The Scotch yoke seems like it would be limited to slower frequency cycles, but it also seems like it could offer a lot of bearing area that could be very reliable with the right bearing bronze and mating sliding surface.

cheers,
Michael

Last edited by Michael Moore; 05-23-2017 at 08:38 PM.
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  #13  
Old 05-23-2017, 08:55 PM
Michael Moore Michael Moore is offline
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https://www.youtube.com/watch?v=ZWihPadDZQg

https://www.youtube.com/watch?v=_xurB-3wI3g

Model 250 Campbell nibbler videos
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  #14  
Old 05-25-2017, 02:07 PM
crystallographic crystallographic is online now
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Quote:
Originally Posted by Michael Moore View Post
Kent, can you use this 3/8" round wool felt from McMaster?

https://www.mcmaster.com/#8767k24/=17raqlt

cheers,
Michael
Thanks, Michael. I ordered some and will see how it drips through.
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  #15  
Old 05-25-2017, 02:51 PM
Michael Moore Michael Moore is offline
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If that felt is too hard/restrictive you might try drilling some small OD holes through it. Or maybe give it a good hammering to loosen it up?
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  #16  
Old 05-25-2017, 02:57 PM
crystallographic crystallographic is online now
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Default Campbell 2536-6 nibbling machine rebuild Part 4 - The Motor and Cast Iron Welding

The 3ph 2hp motor is mounted on a pivot plate with 4 bolts. The plate pivots at the bottom and the top is held to tension the belt with a long adjuster stud, two nuts and washers.
P1010239 copy.jpg
The rusty patch on the right side of the housing is the skid mark where the machine slid to a stop on the road, after falling from the flat bed truck.

The motor spun fine by hand, so I removed it from the frame and took it to the local elect. motor shop - lucky we have a good one here.
They pulled it apart and cleaned it and then called me up and offered to sell me a new one.
I went back down to their shop and found the bearings, armature and all the working to be very nice so I turned down their kind offer and brought the assembled motor back to my shop and set up to weld the 11 inch crack across the housing.

Cast iron welding can be a head scratcher. Conventional cast iron welding methods are :

Ni-Rod - "Weld an inch and pound an hour." A 99% nickel rod available in stick format for AC or DC electric welding, or in bare rods for TIG welding. No pre-heat needed - BUT it MUST be peened after roughly each inch of welding, and peened until you can lay your bare hand on the weld.
NiRod welds are NOT machinable.
I once welded a 56inch crack in a chain-driven hay bailer and hired a kid just to peen my welds. I veed the entire length first and then tacked it up, peening as I tacked. Then I would weld an inch and the kid would sit and pound for an hour until it cooled enough and we'd repeat that .... for about two weeks straight. One root pass and two fill passes was what that job took, and that housing went right back on and it all lined up just right.
...... For some reason I never saw that kid again ...

Cast rods and flux for torch welding - The torch will preheat small heads, manifolds and blocks enough for the torch welding process, without extra preheat ... Clean and vee as needed, then heat the rod and dip it into the flux and use the flux-coated rod to weld with. Machinable and good color match. Can repair valve seats and spark plug holes very nicely.
http://www.tinmantech.com/products/w...g_supplies.php (instructional video on that page, too)
Best material for welding cast iron on the market today - and has been for the 25 + years we have been selling it.
Large casting will need a pre-heat to 650F and then post-heating back to 650F and then a long cool-down.... 24hrs is best.

Special Ni-Rod that needs NO pre-heat and NO peening. MACHINABLE. (Read: unconventional)
I have been using and selling this mystical rod for 25 years. Clean and vee as usual. Tack as usual. Balance the stresses whenever possible, so tack and weld both sides opposite each other whenever possible ... (covered on the dvd, too.) I welded a Toyota 4wd engine back together one time, in the truck, in the snow, and then hand filed the welded pan rail. Cleaned the 22inch weld (welded both sides, so x2), new pan gasket, filled with oil and fired it up. Engine ran fine for another 10 years.
I've welded a number of iron heads, manifolds, blocks and such over the years.

P1030825 c.jpg
Adjuster stud.
P1030845 c.jpg
P1030846 c.jpg
P1030852 c.jpg
P1160035 c.jpg
This is the rod I used to weld this electric motor with - a fully-assembled electric motor.
I veed the crack and made a root pass and a fill pass. Rough weld, I know, but no cracks and it is a very sound repair.
Motor runs just fine, like new in fact. And - I did not have to re-drill the pivot plate and shim it all to fit a new motor. ....


End of part 4 ....
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Last edited by crystallographic; 05-25-2017 at 04:39 PM.
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  #17  
Old 05-27-2017, 11:16 AM
Marc Bourget Marc Bourget is offline
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Side note: Having been to Kent's Shop on several occasions and recalling his description of the recent rain/show season, a relevant story resurfaced in my (imperfect?) memory.

A guy who sells high-end gensets for RVs, recommended improving performance pf windings in motors and alternators, exposed to "high humidity", by "baking" the moisture out of them at the time of O'haul. I don't recall exactly, but I think re-sealing the windings was an included step.

Second point, I have a 12" x 18" x 36" digitally controlled heat treat oven if someone elects the 24 hr. cool down method. Use of the oven is occasional so I'd help you out for the cost of the electricity. (Might work if you're close?)
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