PDA

View Full Version : Re-busted crank...HELP



Martin
04-17-2003, 10:54 PM
When I picked up my Bridgport, it came with a knee crank which had been broken and brazed at least a couple of times.
Today, it broke again and you guessed it, it broke just beyond the braze.
I suspect the heat weakened the steel causing a weak area.
I would like to replace it.
I have seen replacements made by other companies than Bridgeport.
Does anyone have any info as to who, or where I can find one ?
Thanks,
Martin

charlie coghill
04-17-2003, 11:07 PM
Martin,
You might try Reed Tool. I believe they have a web-site. The book that I have is in the shop so I can't help you tonight.
Charlie

CCWKen
04-17-2003, 11:24 PM
Another option is to bite the bullet and go electric!

wierdscience
04-18-2003, 02:04 PM
I fixed one that was broke and I didn't have the pieces of the handle just the hub with the teeth.All I did was take the hub and mount it on a mandrel so I could turn it round I then made a steel bushing with a .250"wall to shrink fit onto the turned hub once it was in place I fabed a steel handle and welded it on from MSC I bought a turned hand peg,this may sound crude but once I was finished it worked out better than the original.I don't know if you have priced any but one for an import mill that I did replace cost me 179.00!I would hate to see what Bridgeport wants.You might try ebay there is a guy in Fla.that sells new import parts they might fit I have also seen a few b-port cranks on there used.

Martin
04-18-2003, 09:50 PM
I thought about triming back the brittle steel portion of the handle and then making a dovetail cut to accomidate a new addition. I may still do that just for a spare, but for now I have BP sending me a new one for $35.00.
I didn't think that was too bad. It certainly ain't resonable but not out of the question seeing how I spent the day grinding down the palm of my hand each time I changed table height...
I like the bushing idea.
Thanks
Martin

SJorgensen
04-19-2003, 01:23 PM
I've often noticed that when handles and levers break, that some thought should be given as to why the thing didn't move as it was designed to move? What caused the load to be so high? I've never owned or used one of these, but if the load is so high shouldn't it have some kind of counterbalance? Machines that require handle breaking force to operate are either underlubricated, out of adjustment, worn out, or poorly designed, or some lock or set screw was forgotten about. And sometimes rusted solid. At least those are the things that usually screw it up for me. I doubt if it required that much effort to move when the machine was on the sales floor being demonstrated to new machinists.
Good luck.
Spence

wierdscience
04-19-2003, 10:14 PM
WOW, BP sending you a new crank for $35.00!You sure they aren't on drugs?Last time I ordered a switch knob and cog belt and shot $65.00 http://bbs.homeshopmachinist.net//biggrin.gif You did say you wanted the whole crank and not just the paint? http://bbs.homeshopmachinist.net//biggrin.gif

yf
04-19-2003, 11:57 PM
Old handwheels off big valves make nice machine cranks when bored and or bushed.
Cheap too.

Martin
04-20-2003, 08:59 PM
W.S.
Actually it was a machine parts sales company which is sending the handle, but it is a BP handle from BP.
It should be here this Tues or Wed.
I'll let you know how it looks.
As for the paint question.....My handle was not painted....
As for the "why they break" response. I would suspect that the reason most of these knee cranks break is for the same reason this one broke. It's cast material and if dropped on concrete enough of times, it will break. And those handles are nitorious for falling off.
Martin

yf
04-21-2003, 01:38 PM
A ball detent or something similar would hold on the cranks until you want them off.

Stepside
04-21-2003, 03:35 PM
Most knee handles on Bridgeports break when somebody uses them as a step when changing collets.

John Foster
04-21-2003, 06:13 PM
As I recall a 1/4 X 20 bolt and washer hold my crank on. Just drill and tap the shaft and the problem is solved. John

Martin
04-21-2003, 09:25 PM
Stepside,
Someone would have to be very short to use the crank as a step. And they would have to use it each time they wanted to change speeds, forward or reverse.....wow....
I never even considered that....
The nerve of some short people.....

I had put out a couple of calls to different companies regarding the knee handle and one called back today. The entire knee crank assembly (assembly ???) was $68.00.
What assembly ? It's a crank handle !!!
He did make sound as though there were a number of items in this "assembly"....
Oh ! now I get it.....screw the knob onto the crank....that's the assembly.....Right?

Oh well....
Martin

wierdscience
04-21-2003, 10:05 PM
Actually forklifts and push carts do a nice job of cleaning those pesty handles right off of all sorts of machinery http://bbs.homeshopmachinist.net//biggrin.gif infact the guys that load out at government sales are real experts at loading equipment at oh say 30mph while hanging the machine by its handwheels on one fork http://bbs.homeshopmachinist.net//biggrin.gif I think they call it lift truck bowling http://bbs.homeshopmachinist.net//biggrin.gif If it ain't broke when you buy it it will be after its loaded http://bbs.homeshopmachinist.net//eek.gif

[This message has been edited by wierdscience (edited 04-21-2003).]