Belt replacement on step pulley j-head

Advice needed.
The drive belt on our step pulley j-head Bridgeport broke after
many years of faithful service. Some time in the past, the
original Bridgeport belt had been replaced with an automotive
belt, and we were able to obtain an exact replacement from Auto
Zone.
Problem is installation. Anyone have a good way to do this
without major disassembly?
As a "quick fix" to finish out the semester, we are currently
running an "emergency fan belt" [about 6.00$] which could be
installed by cutting to length and splicing with special metal
clips. Mill receives only light usage a few nights a week by
students and seems to be working OK.
Has anyone used a link-belt as a long-term replacement? Our mill
supply is attempting to locate a supplier/distributor. Harbor
Freight offers what they call "Accu-Link" for 19.95 see:
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A fast google search indicates this may be a US made product made
by
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Reply to
F. George McDuffee
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Can't help on the disassembly but for those of us with older BP J heads, what is the part number or id on the belt that you got from Auto Zone?
Thanks. Steve.
Reply to
SteveF
If I recall that really is not much of a job. You remove the nuts from the bottom of the motor mounting studs, remove the brake lock handle turn the cam ring handle to the front position and remove the two cam ring pins. remove the screws that hold the belt housing lift the motor off and set it aside pick the belt housing off and swap the old belt for the new one the reverse the above to re-assemble.
About a 30 minute job if I recall.
George
F. George McDuffee wrote:
Reply to
George
Broken belt identified as 4L344 [maker unknown] Auto Zone counterman crossed this to Kelly-Springfield 84340. Given it appears to be a major PITA to replace the belt, I am looking for the equivilant top-of-the line kevlar Gates.
GmcD
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Reply to
F. George McDuffee
Capital idea. Will check it out.
Reply to
F. George McDuffee
Nope!
Reply to
Tom Gardner
If you want to go the linkbelt route try the reinforced urethane one. The brand is right on the tip of my tongue, but unfortunately not attached to the tips of my fingers. However it is sold by McMaster Carr. The company claims it will outlast a regular belt. I can't verify that. However a customer had very poorly designed machine where the drive pulley was way too small and it required major disassembly to replace, and the belt slipped badly because there was no way to adjust it. The company salesman gave me a sample of that belt to try, and I added a spring loaded tensioner that bent the belt the other way between the two pulley to get more wrap on the small one. This is real abuse, a 1-1/2 drive pulley and a back bend the other way but the customer is very happy. He gets two seasons out of the belt and replacing it by opening a link takes just a minute or two. Under normal conditions it just might last a hell of a long time. By the way the coefficient of friction seems higher than a regular belt too so it seems to transmit power better.
Gary H. Lucas
Reply to
Gary H. Lucas
On link belt (not sure if it's necessary in this case)... After some discussion in metalworking in June, I bought some link belt to save pulling the spindle on a lathe I had picked up. I got it here:
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The manufacturer is here:
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At the time I was concerned that I wouldn't be able to run the belt backwards, but it seems ok so far. If it needed to run in reverse very often or under real load, I might reconsider.
Not sure if this helps in your case, but I was pleased when I finally found QC. I thought I was going to buy some belt material from Grainger locally, but found out I didn't have the required business documentation to buy from them. (What's up with that anyway? My money isn't good enough?)
Reply to
xray
I had issues with Grainger as well, but faxing them a copy of my Schedule C, in fact the one that showed a whopping $750 or so net profit for the year when I was busy moving and not consulting, convinced them that I was a business. I like MSC, but there are a few things the Grainger carries that MSC doesn't.
Pete C.
Reply to
Pete C.
I use the powertwist type myself. Both Metal and wood lathe. Powertwist was developed for conveyor belt use - heavy loading. It takes a short work in period and then you reduce the length by a link per x length. It seats nice and the fiber sides grip nicely.
Martin
Reply to
Martin H. Eastburn
The manual pages for belt replacemenrt on the BP is on my website pages. Its under the Technical section under the Bridgeport stuff. Pretty easy and straight forward.
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============================================== Put some color in your cheeks...garden naked! "The original frugal ponder" ~~~~ } ~~~~~~ } ~~~~~~~ }
Reply to
Roy
Not exactly, but the disassembly you need is not major. I just did this last week, I had the head all apart to put in a tach. First, remove the nut and clamping handle that hold the motor on. After dealing with the belt, if still there, lift the motor straight up and off the head. Now, remove 6 socket head screws on the bottom of the belt housing. Also, remove the big nut on the top of the toothed belt pulley. Pry up on the pulley, gently, with two screwdrivers, wiggling until it gets loose, then together to lift the pulley as far as it will go. Now, lift the upper part of the belt housing, and work the toothed pulley off the shaft. The toothed belt can be inspected and replaced if necessary. Loop the new Vee belt around the area where it is to sit, and then put the housing back on, making sure the vee belt is free to come up around the front pulley. This should take no more than 30 minutes even the first time you do it.
Jon
Reply to
Jon Elson
Good link belts are sold by most woodworking suppliers for use as replacement table saw drive belts. I have seen them in the catalogs for woodcraft supply
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and woodworker's supply.
Reply to
woodworker88
FWIW my J head had a new belt put of from the guy I bought it from, here's the numbers.
GoodYear Insta-Power 84340 (4l340)-A32F Flexten
--.- Dave
Reply to
Dave August
Thanks to everyone for the good information.
I have received several emails asking about the "emergency" belt replacement.
The one we used was from O'riley AutoParts -- Victor sku V-320. 1/2 wide belt c. 60 inches [5 feet] long. Belt looks like normal v-belt except it has holes punched every 1/2 inch. Belt is joined by two metal plates and two screws that hold the metal plates together "pinching" the belt. The belt rides high enough in the pullies that the metal clips don't touch. see:
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We are running the mill at 660 rpm using a 3 TPU-322 C6 inserts 1-1/4 diameter R-8 shank face mill to square up some 2 X 3 soft steel stock. We now have about 5 hours of run time and everything seems to be going well.
Notes on installation
(1) While the belt comes with a screwdriver and knife, both are useless. I can't see trying to install one of these on a car in a sleet storm at 3 in the morning.
(2) Use a box cutter / utility knife to trim to length. WD-40 will help the knife cut *MUCH* easier.
(3) On the ends of the belt that go in the clip, try to have about equal amounts of belt beyond the screw holes in each end. We had too much on one side so the other was too thin and tore out. We trimmed both ends and re-assembled with good results.
(4) Use a good full size screw driver with a square tip. The screws require considerable torque to drive through the belt and into the clip.
(5) The picture shows the clip with the screw heads to the outside. We had to mount the clips with the head to the inside and the threaded clip to the outside [of the belt] to provide clearence at the bottom of the pully.
(6) Don't cut the belt too short. Plan on making at least two tries.
(7) There is another type of emergency fanbelt available. Its a plastic tube with a special oneway plug to splice into a loop. I don't know how these would work. tubular
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other types
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Reply to
F. George McDuffee
Womans nylon stockings work surprisingly well as replacement fanbelts.
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner Asch
Gunner Asch wrote in news: snipped-for-privacy@4ax.com:
Ahh. So that's how you explain the stray pair that turns up in the glove box.
Reply to
D Murphy
| Gunner Asch wrote in | news: snipped-for-privacy@4ax.com: | | | Womans nylon stockings work surprisingly well as replacement | | fanbelts. | | Ahh. So that's how you explain the stray pair that turns up in the | glove box.
Wait, wait - true story.
I'm in my early 20's and parking at a local makeout spot with my girlfriend, and for some unremembered reason she opens the glovebox.
"What the hell are these?" Uh, they look like pantyhose. Why? "They're NOT mine." Oh. Uh, they *must* be because they're not mine. "%$_&(%&^(^@#!!!"
Turns out, as I discover a couple of weeks later, my sister had borrowed my car and her friend had changed in the front seat on the way to the beach and left her panty hose in my glovebox - like 2 months earlier. Of course I hadn't looked in my glove box, I only go in there to change the registration renewal, I dont' keep anything useful in there.
I tried explaining all that, but you know how some women get...
moT
Reply to
Tom Accuosti
I never could sucessfully explain to my Dad where the single blue contact lens, the half empty bottle of Sudden Discomfort, the size 1 panties, the size 48DD bra (4 hook) and the impressivly large stack of empty condom wrappers that he found under the back seat of his old Plymouth Fury 3 came from, when he discovered them after removing the seat for some reason or another. Particularly when he reminded me he had bought the car new......
Must have been one hell of an after hours party on the old assembly line.
Sigh..he didnt buy that either....
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner

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