Chicago Dreis&Krump Box&Pan brake rebuild

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Firestopper

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I recently purchased this unit sight unseen from the City of Gilbert AZ. I went through Public Auctions for the bid process and after a little bid war with what appeared to be a pawn shop (based on the bidders handle) I was high bid at $1586.xx after taxes and processing fee. There was four photos (poor quality) along with the auction so kinda limited on my end. This model is BPO 614-6 with a Serial No. 316138. I found out from Dreis&Krump that the machine was sold to the USAF back in 1977. Its a 6ft (73") unit with a max bending capacity of 14 gauge mild steel across the entire 73". I doubt I will ever need to build a box that long so I could be able to fold thicker narrower sections including aluminum. Now for the risks on buying a brake sight unseen: Many knuckleheads will bend/brake items such as round bar and thick flat strap using cheaters for leverage. This poor practice can result in a "sprung" condition ruining a brake, or damaging Nose bars and hardened bottom bars as well as bending bars. This model is a BPO, "O"meaning optional bolt on hardened bars. Thats a good thing considering the other BP models have welded bars. The bottom bar has the ability to be flipped (like shear blades) to expose a virgin side. All the dings on worn bars transfer to the bends on softer material such as aluminum once clamped. The same goes for damaged Nose bars.The Nose bars can be reworked on a mill (I'm hoping) and the finger extensions can be made from 3/4" thick CR flat bar on a mill and vary in different widths (3",4",5"and 6") determined by the width of the Nose bar. These can also be "sprung" when abused. At first I was under the impression I was missing one finger, but after receiving literature from Dreis, I was pleased to find the machines complete.
I made the 130+ mile drive after shift to pick up the unit only to find the forklift operator forked it from the upper clamp to remove the machine from inside storage. This is not advisable and could damage the unit. I had loaded any rigging equipment I thought might be need to load the machine onto a 14K dump trailer I was pulling (little tall).
After removing all the fingers to lighten/balance the pick, I rigged it for picking and that went smooth. Secured the load for my 130+ mile drive home. I used every strap I keep in the rig.
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I got home around 2:30 pm and backed in the trailer for the night. I was too tired to unload the unit as I had worked a 24 hour shift that kept us up pretty much all night at explosion/fire that required 4,000 GPM and fifty firefighters. I had it made compared to the guys on the ground handling 2.5" hand lines. It was a defensive fire and we had exposures to protect. I was up 110' operating a Master stream from bucket ladder truck with onboard air (no SCBA required) plugged into my face mask :). I was pushing 800 GPM from the toggle switch controlling the nozzle so a cake walk compare to the young bucks on the ground. The explosion took place at a Jajoba processing plant that operated 24/7. http://www.tucsonnewsnow.com/story/36802022/5-hospitalized-after-building-explosion-fire. We did have a substantial amount of transmission lines to avoid as there was a power substation in close proximity. I could feel/hear the energy coming off those lines..Creepy feeling. Perhaps all in my head, who knows.
Anyway, back to the brake,
Unloading the machine from the bottom: I had place some 4"cribbing under the brake running perpendicular to the trailer stringer running parallel to the heavy load at the time of loading. I also didn't want the machine to slide on the metal deck incase of emergency braking. This proved to be very helpful when I unloaded alone. I was able to use 8' fork extensions made some years ago from 6" channel. I was able to approach from the end but needed to drag the unit closer to the end of trailer. This thing is top heavy and off CG as the top clamp section was dislodge when the guy forked it from the bottom portion of the top clamp. The unit wanted to rotate counter clockwise co large C-clamps secured the lower stand to the forks as well as a rigging chain to assist in pulling the machine closer to the trailers a$$ end.

Lifting and gently pulling machine to trailers edge allowing the 8' forks to capture the front stand.
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Got it on the ground without drama.
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Next up was to reseat the upper clamp back onto the adjusting saddles.
I cribbed the unit leaving the fork extensions in place, then got a shorter 2X4 to use as a spacer under the upper clamp and gently raised the upper clamp to clear the saddle. I then raised the clamp arms using the cam action to line up the saddles and lowered the clamp into position. This went very easy and smooth.

Here you can see the misalignment of the adjuster. Luckily the connecting threaded rod is robust at 2" and supported the knucklehead poor choice of method to move out the machine. Before I reseated, I took the adjuster apart to clean the hard dried grease making it hard to turn. This was put back dry for now and moves freely.
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Short section of 2x4 to clear the finger extension mounts under the upper clamp.
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Raised it up just enough to rotate the cam lever to align the mouse hole over the L/R adjuster.
Once aligned, I gently lowered the upper clam to its home location. You can see the large clamp
adjustment threaded rod that connects the upper clamp to the lower portion of the table. The robust
design saved the brake from a total failed forklift pick. The sides are 1" thick plates as is the top end plates.
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Here you can see the machined bar that supports the finger extensions (behind the 2x4). The
2x4 prevented fork contact during lifting of top clamp. Also notice the table and bending leaf hardened
Bar. The machine will require a bending angle bar to bend to capacity. A common piece of 1/4"x2" angle should
do the trick so long as its straight.
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A total of 15 fingers and one custom made. I still need to inspect for damage, but right off the bat
they will beed to have the bottoms reconditioned. I also noticed one with damage from bending rod:mad:
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Spent a full day trying to adjust but found myself removing hardware to clean multiple coats of paint.
I also removed the table hardened bar to flip, the back side a virgin. The problem is two or three holes where drilled at the factory slightly misaligned. I should be able to slot them slightly using a mag drill. I was unsuccessful in aligning the leaf to the table by .0858". I decided to further tear down the folding leaf and inspect the pivot point for excessive wear that could be preventing the realignment. Working alone takes creative thinking at times when picking heavy items that want to rotate such as the leaf. I rotated the leaf 180º and secured a rigging chain and took up slack, then removed the two counter weight prior to removing the ten bolts.
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The pins where driven out using a bronze rod after the leaf was removed. They came out easy but then again, I used "Free all" penetrant the day prior. The paint was so thick a socket would not fit but a wire wheel took care of that. I wouldn't be surprised if lead base paint was used somewhere between those coats.
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Bronzed bearings as they are called in the manual. The pin fit snuggly into the cast bracket but very loose in the bushings. An oil journal was noted around the center and two legs front/back for the oiler that was painted over.
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These 3M products remove the layers of paint without cutting into base metal. Kinda expensive, but worth it and the green ones last a long time. The worn out one was used on several projects and is ready to be tossed.
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The pivot pins have flat spots for the set screws to bite onto. Better than just round as this can become problematic to remove if a burr is encountered. I have delt with that situation (as many other have) its a PITA. They where thinking on this one.
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Waiting on parts quote and I might try to flame straighten the leaf section but probably wait to do it on machine. Back to the lathe/mill cart build.
Incidentally, I used the said cart (prematurely) as a support cart during inspection and teardown. Rolls nice under weight.
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Gona also get some quotes for sand blasting. I don't want to install/press new bushings prior to blasting. Its really a toss up, spending more money on parts/blasting and paint, or reassemble after new bushings to ensure the unit it still salvageable/within tolerances, then disassemble if it proves to be good.:headache:

BTW, there is very limited information available on these units, If any tin benders on the site, please chime in. Any advice is always welcomed good/bad or indifferent.
I'm always trying to learn and share my experiences.
Thanks for looking, more to come later.
Turn and Burn!
Paco

Thanks for looking

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Paco, looking good so far. Hope she isn't sprung too much. I'm eventually going to get a box/pan break for my shop. But not until I move into a bigger place.
Question: How will you recondition the bottom of the fingers?
 
Nice work so far Paco, although I gotta say your work is always exquisite. I have an older (and smaller) D&K Chicago as well except at 36". Different style than yours with but also 14ga capacity. Mine came with no fingers so I ended up making some from scratch. The thread is here

http://www.hobby-machinist.com/threads/brake-fingers.50968/#post-431868

for what it's worth. I doubt they'll stand up to hard use, but they do work just fine for the small stuff I fool around with. Looking forward to seeing how your machine finishes up.

-frank

edit: capacity of mine is actually 16 ga, not 14ga as stated above
 
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Paco, looking good so far. Hope she isn't sprung too much. I'm eventually going to get a box/pan break for my shop. But not until I move into a bigger place.
Question: How will you recondition the bottom of the fingers?

Thanks gi_984, The Nose bars (fingers) are semi hardened. Too hard and they would fracture under use. I'm hoping to jig them up one at a time and face mill. I would need to find the worst one and mill clean. Once I have a "standard", I would need to mill the same amount off the remaining bars to maintain even clamping force and alignment. I just ordered the pins and bushing and one left hand screw (it was missing) and the tally came to $150 with shipping. While I as on the phone with Mona, I asked about the cost of Nose Bars, she informed me they run $21.00/inch:oops:. So yea, I'll give face milling (insert type) a try. On the finger extensions, I think a 3/4" CR flat bar would work well with minimal machining required. I'll post that when I cross that bridge tho. BTW, Chicago D&K use hot rolled bar for finger extensions.

Nice work so far Paco, although I gotta say your work is always exquisite. I have an older (and smaller) D&K Chicago as well except at 36". Different style than yours with but also 14ga capacity. Mine came with no fingers so I ended up making some from scratch. The thread is here

http://www.hobby-machinist.com/threads/brake-fingers.50968/#post-431868

for what it's worth. I doubt they'll stand up to hard use, but they do work just fine for the small stuff I fool around with. Looking forward to seeing how your machine finishes up.

-frank

Thank you Frank,

I cant believe I hadn't seen you post on your box & pan brake, Very nice indeed. I skimmed though you post but will read it in detail. Your results are amazing! Nice work man. The model I have is no longer offered, but they still support all the parts. Hopefully, I can get her back in within tolerances. If I cant flame straighten the last .090", I plan on machining down the right pivot bracket and shim accordingly. I cranked pretty good on the torsion bar to the rear of the table but would hate to over do it resulting in FUBAR. I have done pretty complicated flame straightening back in the early 80's on submarines, but that was long ago and I was at my peak of my learning curve. These days I cant remember what I ate for dinner two days ago hahah. I've totally and officially ran out or RAM a few years ago. It would be awesome if I could simply plug in a thumb drive into my head and update RAM, but thats life brother, don't get old.;)

Thanks for the encouragement and input gents, I'll keep you posted on progress.
 
Nice brake. My money's on you getting it back to spec. Hey, if it was easy everybody would be doing it. Cheers, Mike
 
Thanks Mike,
I have a plan "B" that would require machining one pivot bracket that might provide better control.
I repurposed an old threaded shaft to drive out the worn bushings. The were two piece set with the gap in the middle that served as a oil journal. The bushings also had small groves towards the center.
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Awaiting parts at the moment.
 
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I received the replacement apron bearings/bushings and pivot pins from Dreis & Krump today. Turns out they use Oilite bushings now so no longer require the 30W machine oil to be shot through the ball oiler located at the top of the main pivot point. The question I have for you folks is, while I have the machine apart, should I drill out the old ball oiler, press in new bushing, drill small hole through the bushing (clean off any burrs) then install new ball oiler or will the Oilite provide enough lubricity on its own? I ask only because it's my understanding that the Oilite material only "sweats" oil under friction and temp then reabsorbs the oil under static conditions. The pivot action will never produce any measurable temperature change when bending metal. I'm thinking a little outside oil might keep things from wearing out prematurely but what say you?

This is the original left pin and two piece bushing that was removed. The pin was sloppy and worn about .008" at its worst spot.
The old two piece bushings have two oil journals machined 180º apart and gapped at the center where the ball oiler is located.
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Here you can see the ball oiler centered on the main pivot body. Again, the two piece bushing where gapped at the center allowing oil to coat the shaft then captured by the small journals on both bushings. This is originally how the machine was built in 1977.
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The replacement Oilite bushings are one piece with no hole or journals.
The new pins fit snug but rotate freely in the new bushings.
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Now would be the time to reinstate the ball oiler if at all. The components are heavy and I only want to do this once so any advice would be very much appreciated.
BTW, in speaking with Dreis/Krump's engineer, the tolerance for all pins and bushings on this machine are .001" per inch of pins diameter. I ordered the bushings/bearings for the left/right side clamp, pivot shaft and clamp handle assemblies. They where all very sloppy. The shafts all measured good so the old bushings did their job unlike the apron pivot points.
Thanks for any response in advance.
 
Just found this thread. Nice buy Paco.

I started to vote for the reinstatement of the oilers but, after thinking about it a little more, I'm not so sure.

How much service is that brake going to see in your lifetime (another 50 years). Would you ever wear them to the point that replacement was called for?

What are the trade offs?

Will more oil add to the life of the joint? I would expect so, as long as no contamination is introduced in the oiling procedure. Contamination isn't much of a problem considering the resident PM mechanic.

You could band saw a slot, perpendicular to the axis, at mid length and about half way across each bushing. Then cut spiral reliefs in both halves with a rotary tool to distribute the oil. Remove all burrs and shavings and there you go.

I think I'd reinstate the oilers, but I don't think it's a big deal either way.

Most importantly, there is about zero chance the brake will ever be abused (in your shop) so it's going to last a lifetime either way.

Regarding the leaf alignment, I don't understand where/how/what the problem is. When you revisit that area of the refurbishment please clarify what is to be aligned and what is out/where. Thanks, as always.
 
I like the idea of oiling joints, fresh oil flushes out particles from wear thereby removing abrasive material. Drilling the one piece bushings isn't going to give you a reservoir. I'd be tempted to cut the new bushing and make two that would install as the old ones did.

Greg
 
I'm attaching the Oillite guide which should help you decide which way to go.
I wonder which grade of material the OEM sold you?
 

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