Today, I made a simple modification to the drawbar on my Index Model 40H vertical mill.
The original arrangement on the mill requires that the arbor or collet to be released by loosening the drawbar nut and hitting the drawbar with a hammer. I think this is really hard on the bearings.
For a few years now, I have been wanting to modify the spindle and the drawbar to have the arbor or collet pushed out by turning the drawbar counterclockwise like my other mill.
As I am currently reassembling the mill after painting, I thought that it would be a good time to modify the spindle and drawbar.
When I was measuring the spindle to come up with a design, I noticed that the collet end of the spindle was drilled first (approximately 0.90" dia.) and then the B&S 9 taper was cut. The 0.90" bore extends a short distance beyond the taper and then necks down to 0.625" dia.. When I installed and cinched down the collet in the spindle, I noticed that there is a void above the collet about 0.50" long and about 0.90" dia. This gave me the idea to put a shoulder or collar on the bottom end of the drawbar instead of the top. This would be much simpler than modifying the upper section of the spindle and another drawbar. I silver soldered a collar on the bottom end of the old drawbar to try out the idea. I also squared up the shoulder inside the spindle to get a smoother action (the shoulder was angled). ( Note: The collet has to be screwed all the way up to the collar on the drawbar and then tighten the drawbar nut.) To release the collet, you loosen the drawbar nut and turn the drawbar counterclockwise.
It works great. This was a really simple modification.
Tomorrow, I will cut some flats on the top end of the drawbar and make a thin brass washer to go between the drawbar collar and the spindle shoulder.
As I was writing this, It occurs to me that this mod. might work an other models and brands of mills that do not have the push-out drawbars. (I have a Shoptask, I'll check it tomorrow)
Hope this helps someone else.
mhooper
The original arrangement on the mill requires that the arbor or collet to be released by loosening the drawbar nut and hitting the drawbar with a hammer. I think this is really hard on the bearings.
For a few years now, I have been wanting to modify the spindle and the drawbar to have the arbor or collet pushed out by turning the drawbar counterclockwise like my other mill.
As I am currently reassembling the mill after painting, I thought that it would be a good time to modify the spindle and drawbar.
When I was measuring the spindle to come up with a design, I noticed that the collet end of the spindle was drilled first (approximately 0.90" dia.) and then the B&S 9 taper was cut. The 0.90" bore extends a short distance beyond the taper and then necks down to 0.625" dia.. When I installed and cinched down the collet in the spindle, I noticed that there is a void above the collet about 0.50" long and about 0.90" dia. This gave me the idea to put a shoulder or collar on the bottom end of the drawbar instead of the top. This would be much simpler than modifying the upper section of the spindle and another drawbar. I silver soldered a collar on the bottom end of the old drawbar to try out the idea. I also squared up the shoulder inside the spindle to get a smoother action (the shoulder was angled). ( Note: The collet has to be screwed all the way up to the collar on the drawbar and then tighten the drawbar nut.) To release the collet, you loosen the drawbar nut and turn the drawbar counterclockwise.
It works great. This was a really simple modification.
Tomorrow, I will cut some flats on the top end of the drawbar and make a thin brass washer to go between the drawbar collar and the spindle shoulder.
As I was writing this, It occurs to me that this mod. might work an other models and brands of mills that do not have the push-out drawbars. (I have a Shoptask, I'll check it tomorrow)
Hope this helps someone else.
mhooper
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