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removing collars?

Started by leastofthese, December 19, 2010, 03:01:30 PM

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leastofthese

i am trying to get my saw tuned up, in reading at doc jeff's  sawdoc page he said worn collars are the most common problem. so i took my collar off and did the chalk test, which appears to show a worn bearing surface. and the same on the fast collar. now about removing the fast collar, does it come off the shaft on the threaded end. it looks like something like a keyway and key on the shaft. but i can't see any crack for movement at the collar and shaft. i know there are many here that have had this collar off.thanks for the help.

Carpenter

     There is generally no need to remove the fast collar, it can be trued up right on the mill.  I trued mine up with a two way vice with a lathe cutting bit chucked into it.  I had to build a stand attached to the husk at the right hight for the cutter, and the cutter needs to be at the center of the collar for height.  ( I found out the hard way that if the cutter is above center, it will gouge the collar) slightly below center might work.  Also, a three way moveable vice would work better, but, all I had was a two. 
      You can take the whole mandrel to a machine shop, they can true it up on a lathe, it accomplishes the same thing.  The disadvantage of truing the collar on a lathe is that the lathe will true it to the center of the surface of the mandrel shaft.  When the mandrel is on the mill, the bearings may shove the shaft one way or another, and it will actually run on the center of the bearings.  It should be with in a few thousanths of the same center, but I believe it makes a difference.  The loose collar can be trued on the mill as well, (although I had mine trued on a lathe), I'm relatively sure that you would be able to turn the loose collar backwards on the mandrel and put the nut back on and true that face as well.  Also, your collars must be the same size,  one way to ensure that is to put them together without the saw blade in between them and cut them with the mill cutter.
     If you do need to remove the fast collar, they are often a friction fit on the mandrel.  (I'm sure that there are other ways to attach a fast collar, but this is one that I am familiar with, also, I have never done this but I've talked with a guy who has)  He, bores the hole in the collar a few thousanths smaller than the part of the mandrel that the collar goes on, and the mandrel has a shoulder that the collar fits tight against.  Then the collar is heated so that it expands and fit onto the mandrel.  When it cools it is tight.  It can come back off with a lot of heat and a lot of pressure but you may have to cut it off with a tourch.  At any rate after the new collar cools, it will still need to be trued up to the mandrel.  So, there may be no need to take it off at all. 
   
     Hope this helps.  I couldn't find any pictures of the jig I made to true up the collar, or I'd post them.  It did work and wasn't very difficult, probably sounds more difficult than it was.  And, it did help the saw to run true. 


leastofthese

i can weld, cut,fit and work really hard, but i don't know about machining my own collar. thanks for the reply and i'm trying to picture how u did it
.

Carpenter

     I couldn't find a picture so I drew one.




     It looks like some of the detail got left out in the scan.  But, this is a two way moveable machinists vice with a lathe cutter chucked in it. (It can move both forward and side to side, but it can't rotate so you have to get the cutting angle right before bolting it on.) Like I said before a three way would be a lot more convenient.  I just built a stand out of 2x12s at the right height for the cutter and screwed everything to my husk and ways.  I have a wooden husk so that was easy.  Then I set the vice with the cutter in it at the same angle as the face of the collar ( you know from reading the manual that the inside of the collar needs to be relieved a few thousanths) and bolted it to the 2x12 platform.  (Also, the 2x12s were all doubled to minimize flex.)  Then with the arbor turning I could slowly move the cutter head into it until it made a cut all the way around the face of the collar.  It's really only the outer half inch that you are worried about, it needs to be at a slight taper so that the blade only touches the very outer edge, everything else just needs to be relieved more than that.  So, if you don't cut the outer edge too far and everything else is already relieved, all you have to do is touch it with the cutter bit.
     A saw doc pointed me in this direction, I'm sure I had a blank confused look on my face at first too. 


     I see when I previewed the post that the picture is turned 90 degrees from where it should be, so you'll have to tilt your head. 

Dave_

Great drawing, Carpenter.  Not only can you cut, but you can draw 8)  Also, that's a great idea for truing the collar face.

ladylake

What do these collars do?   Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

Ron Wenrich

They support the saw.  If you have a spot that dishes away from the saw, then your collar has a weak spot, and it doesn't support as well.  That does effect how a saw runs, especially if you're turning at high speeds.

We have a machinist come in and do it on the mill.  We also send the outside collar with him so he can turn that one at the shop.  We have an extra collar so we don't lose production time.
Never under estimate the power of stupid people in large groups.

leastofthese

dropped my saw off at the saw doc in sherevport, la. yesterday. needs to be rehammered. showed him my loose collar and he said definitely needs truing up. he also stressed that the outside diameter of the two collars has to be the same or it will make the saw lead in or out. so i'm looking hard at your drawing carp. i need to get in touch with my machinist  friend and show him your pic. lord willing i'll be able to turn the fast collar like you did. still no suggestions for removing the fast collar.

D._Frederick

Least.-

You can heat the collar with a heating torch and maybe drive it off, but you will need to have a machinist make a new collar and shrink fit it back on the arbor shaft.

I guess that I don't understand why you want to take the fixed collar off if it is tight and not damaged. If the collar needs turning, take the arbor off of the mill husk and take it to a machine shop. 

Ron Wenrich

I've never heard of anyone taking off the fast collar either.  Not recommended.

Never under estimate the power of stupid people in large groups.

bandmiller2

The fast collar should not be removed from the arbor,even if you did and pressed [pounded] it back on it wouldn't be true.Many hammersmiths and millrights have a tool for trueing the collars on the mill which is the best way.Most of the arbor shafts are long its hard to find a shop with a lath bed long enough to turn them.What Carpenter did is a good fix.Insted of a tool bit, a toolpost type grinder will also true them as usally not much has to be removed.Frank C.
A man armed with common sense is packing a big piece

leastofthese

the reason i was thinking to remove the fast collar was because of the length of the arbor. didn't really know that it was basically one piece. so i'm going to talk to my machinist friend about truing it on the mill or see if his lathe can hold a 5 foot shaft. thanks for all the info.

sjh

I took my collers off when they were bad. You need 2 things. A torch with a rosebud and some thing to use as a press. Once the collar is heated it will pop off. As someone else said the collar is pressed on. That does not mean like pressed punched on in a press. The collar hole is bigger than the shaft. To reinstall you need dry ice on the shaft and a very warm collar. When I dropped the collar on my shaft it had a 1/8" gap before cooling/shrinking of parts. My saw ran true after I had it done.

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