Bad pancake motor options
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  1. #1
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    Default Bad pancake motor options

    I'm acquiring a Bridgeport milling machine from a scrap yard. It's a J head step pulley with a 1 HP 3 phase Fairbanks Morse pancake motor. The covers on the motor are open and it looks nasty so I'm guessing the motor is bad and that's why it was scrapped. The rest of the machine looks to be in good shape. If it is indeed bad would I be better served to repair, replace with same or upgrade to a new more conventional motor such as a Baldor or equivalent? This is my first Bridgeport and it's free so I'm prepared to spend some $ within reason. This is going to be my home shop machine so I want to do it right the first time. Any advice would be greatly appreciated.

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    I'd take it to a motor repair shop and get a quote to fix it first. It might be pricey but it'll get you up and running. Those pancake motors work very well for their class of machining IMO.

    You can also check with some BP repair shops (H&W repair's a good one) if they can sell you a spare. I'd also be on the look-out for a 2J head with the reeves drive. Even if it needs repairs, the variable speed option is super handy and they give you an extra 1/2 Horse of power. In all of the BP knee mills we've had, the only issue we had to live with due to cost/hastle to repair was wear in the splines. Bushings, belts, shafts, motors, and gears can all be repaired on these machines without too much effort.

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    Second what Naegle said. My local motor guy rebuilds em for $20-40 per hp. Min $125. Depending on the mood of your guy it should be cheap to fix. Rebuilding irrigation stuff is %50 of their business and they get pretty lonely this time of yr.

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    Quote Originally Posted by Aejgx6 View Post
    Second what Naegle said. My local motor guy rebuilds em for $20-40 per hp. Min $125. Depending on the mood of your guy it should be cheap to fix. Rebuilding irrigation stuff is %50 of their business and they get pretty lonely this time of yr.
    +1 BirdPorts have the SPACE to put just about ANYTHING up there - even Dee Cee treadmill alleged motors (not MY cuppa),

    ..but the even slightly shorter shaft-axis "pancake" configuration, lest one forget the obvious, hangs less MASS as far out on what becomes a long lever-arm when yah need to swivel the whole works over at an angle.

    "Obvious" advantage if yah think it through.

    Or ever had to replace any overly worn or abused to breakage positioning and locking mechanism bits.

    I'd agree yah should ship it to that sort of rebuilder as is able to do good work at reasonable cost and "keep it OEM".

    BeePee factory might have been kinda stingy on power, but they did a fair decent job of balancing all that for what it was they shipped.

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    I have a step pulley head at home, and
    I’ve ran variable speed heads at work.
    If you’ve never ran a variable speed
    head, You might try that before you
    just swap heads, because In my opinion
    the variable speed heads are rattle traps.
    My Step Pulley Head is ultra quiet and
    I love it. The speed of the step pulley
    head can be adjusted with a VFD or
    Variable Frequency Drive, I have a
    Lenze VFD, you can see them if you look
    up ShadonHKW youtube channel, he uses
    a VFD on each of his machines.
    I’m going to try and use a
    Rotary Phase Converter to power all my
    machines, and just use the VFD to
    Adjust the spindle speed on the
    Bridgeports head only. It’s really nice
    being able to adjust the speed on the
    fly with the VFD instead of spending
    countless time changing belt positons.

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  7. #6
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    This is just going to be a home shop mill and I have little to no milling experience. Me and the kid want to rebuild old motorcycles etc. Adding this to the shop will add to our ability to make parts as needed. My plan is to keep it as original and simple as possible. Definitely going to be running it through a VFD so not intending to change out heads. Only upgrades planned are fixing power table feed and adding a DRO.
    img_0583.jpg

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    IMO every machine shop, hobby pro or otherwise, needs a good mill, a good lathe, and some kind of phase converter. 3 phase power is a must when you're cutting metal with anything 1HP or higher.

    One other thought is that if you're just starting out, fix or replace what's there but avoid retrofits (patching odd motors onto the head). I've seen a lot of poorly executed modifications on machine tools that the owner was probably really proud of, but they just didn't compare in function or durability to what the OEM supplied or recommended. I'm always impressed with how smooth the old pancake motors reverse. It makes power tapping so much easier.

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    Good news bad news on mill. Good news is it runs! Wired up a vfd , hit the power and she started right up. Wear seems minimal, seems to be zero play in the spindle. Split nuts need some tightening up. Included full set of r8 collets plus 2 jacobs super chucks, a 6" curt vice and a 4" unidentified vice, but seems very good. The bad news is the ram is frozen, the head swivel screw is missing so i'm assuming it's broken off inside, cam ring is broken but still functional, table power feed needs work, someone put grease in oil zerks (already blew them out and pumped way oil in), knee crank is missing and it's pretty grungy. Did a test facing run on 3" square aluminum and it's really pretty close! Can barely feel any ridges. A buddy has the test gauges to dial it in. I'm pretty happy so far. Total investment at this point is $160 for a tow truck to lift it off trailer and set it in front of my garage.

    Any suggestions on freeing the ram? Already soaking everything in kroil.

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    Ram on mine was frozen when I got it. Clear evidence of it being left outside uncovered for a while, water in the head being a clue, so primary issue was probably corrosion related.

    Cleaning all the exposed surfaces of the ram, removing the locking devices and lever feed followed by heavy anointing with Plus Gas for a week had no effect despite persuasion from a big dead-blow hammer. So I stripped the head, ram and turret off and parked it on the shop floor jacked up at around 55° tilt longways. Turret down so the Plus Gas had somewhere to run. Flipped it over every morning and evening to give the turret a few whacks with big dead-blow hammer. Flipped it back and re-anointed with Plus Gas. After a week and a half or so I discovered that the turret had slid about half its width down the ram overnight. Now we were cooking with gas. Re-anointing and some careful whacking with the dead blow got it shifting back and fort over the jammed area. Bit more clean-up and she was off.

    In retrospect things might have gone faster if I'd made a mount to bolt the assembly up with the ram vertical and a few inches above the floor. More weight for gravity to get things moving that way.

    Obviously don't hit the castings with an ordinary hammer, I like my Thor nylon faced dead blows for shifting'n adjusting but I guess a nicely aligned alloy drift will do. Seriously not in favour of improvised screw, hydraulic or farm jack systems as its very hard to get forces on the best line without considerable manufacturing effort to make suitable push blocks.

    Clive

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    What you call covers on the motor are called belt guard covers. You do not need those.

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    The rams and turrets on these mills sometimes go unused by owners that just see the machine for it's X-Y-Z capabilities. When they need to mill an angle they would just buy an expensive angled end mill or do all the set-up with the vise, and those same guys won't regularly tram in the vise and start scratching their heads when parts start coming out un-square. Once you get it all free'd up, there's a ton of utility built into these machines. You might only be able to move the table in a small window, but between the ram and the turret, you can reach all over a very large area.

    We've had a couple stuck rams in the past. Use a fair amount of penetrating fluid, and a decent sized rubber mallet will help 'shock' the joints. You might also have a broken pinion gear. On ours we had to have someone incrementally rotate it while others inched the ram out so that it didn't hang up hold back the ram. Ideally, I'd get the turret/ram all apart so you can clean/inspect, and repair everything. Don't just loosen it up and call it good.

    In tight quarters, I've also used a ratchet strap to compress a ram out of it's dovetail. Tie it into a ring with one end around the column and the other around the end of the ram. Solid and steady pressure can do more than just beating on it.

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    I'm thinking disassembly might be the way to go especially since I've got something broken in the worm gear assembly in the head. Since I'm probably going to pull the head off I may as well tear the whole top off. Any idea on how much the turret and ram weigh? I do have an engine hoist that should reach if I extend it out all the way but I believe that limits me to 500 lbs.

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    Head 200#
    Ram Adapter 90#
    Ram 218#
    Turret 214#
    Column 715#
    Knee 257#
    Saddle 142#
    48" Table 365#
    Total 2201#

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    Good news! Got the ram free. Took a lot of Kroil and a lot of beating with a BFH! Once I saw movement I got out the big pipe wrench and it finally let loose. Cleaned it best I can and greased it up. Figured I'd work it every day for the forseeable future. Already pretty smooth except it gets tight the last few inches when i move it to the back. I can live with that.

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    Quote Originally Posted by Thom1960 View Post
    Good news! Got the ram free..... Cleaned it best I can and greased it up....
    Best to use petroleum jelly or Vasoline.
    Grease will gum up and dry over time.
    Vasoline will not.

    -Doozer

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    Quote Originally Posted by M.B. Naegle View Post
    ..... 2J head with the reeves drive. Even if it needs repairs, the variable speed option is super handy and they give you an extra 1/2 Horse of power.....
    You really do not get to use that extra 1/2 horsepower.
    All it does is heat up your shop. The Reeves pulley
    is spring loaded to pinch the belt, and that makes
    friction and heat. That is why BP upped the power
    for the motor, because they knew this type of Reeves
    drive has very poor efficiency.

    --Doozer


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