[How-To] Enco drawbar issue

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RobSarasota

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First post for this forum but have been reading many of the other posts. Just bought an old Enco benchtop mill, model 105-1110. Overall it was in good shape. I was going to replace the drawbar which I saw was in poor shape prior to buying. Found the drawbar was slightly stuck in the spindle shaft but there was some movement with it. I had to lightly drive it out. The old drawbar was 7/16 inch diameter and the length was 16 1/2 inches. Could not find any that length so I ordered an 18 1/2 inch long bar and was going to cut it off to the needed length and rethread. Did not want to use a 2 inch spacer to make up for it being too long. New drawbar will not fit into the spindle drawbar shaft. Old drawbar measures .432 diameter and was tight. The new bar is exact at 7/16th inch or .438. Need some clearance so a 7/16 drill bit is not big enough. Was thinking about running a long 29/64th (.453) drill bit to enlarge the drawbar shaft. I would appreciate any other suggestions or comments. Planning to use a drill motor to open the shaft by about .020 inch. Thanks
 
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If it was me I would just remove the 6 thou off of the new bar. Easy enough to do with a file and some paper.
 
No lathe available? Good reason as any to buy one! :) I wouldn't drill the spindle
 
There is a key in the spindle
the key keeps the tools from slipping
Do not drill out the spindle hole
 
dirty tools said:
There is a key in the spindle
the key keeps the tools from slipping
Do not drill out the spindle hole
Click to expand...
Not an issue will collet spinning. If I can't get the draw bar into the spindle shaft hole, how then can I draw the collet up to snug it in place? I need to get the new draw bar in and it will not go in.
 
UPDATE TO CLARIFY ISSUE BETTER

Thinking previous owner likely had an issue with the drawbar getting loose and spinning and this caused burrs and or galling to the drawbar shaft hole. Old drawbar was bad and needed to be replaced. The old drawbar was very tight in the hole and it had an approximately .432 diameter. I say approximate because it had been welded in the middle of the drawbar but checking it in v-blocks showed it was straight. The new drawbar is .438 diameter and will definitely not fit in or even start to enter shaft hole. If all new drawbars are going to come in at around .438 diameter, then opening up the spindle drawbar hole should be the only option. Reducing the OD of the drawbar will work, but it also reduces the OD of the threads for screwing into the collets. I have no idea as to how much material would need to be removed from the drawbar diameter to enable it to freely move with the galling/burrs that are currently in the shaft hole. The drawbar shaft hole is 15 inches long through the spindle and then opens up in the collet section. I checked SAE versus metric sizes and for the most part standard sizes in SAE and metric are almost identical in the sizes that I am dealing with such as: 11mm equals .433; and 11.5mm equals .453, which is the same as a 29/64 drill bit size.
 
I used to have a RF clone mill like yours with an MT3 taper and the drawbar if not snugged up actually rattled in the spindle.
Does your mill have an R8 or MT3 taper?
R8 takes a 7/16-20 thread whereas MT3 takes either 3/8-16 or M12-1.75
 
DavidR8 said:
I used to have a RF clone mill like yours with an MT3 taper and the drawbar if not snugged up actually rattled in the spindle.
Does your mill have an R8 or MT3 taper?
R8 takes a 7/16-20 thread whereas MT3 takes either 3/8-16 or M12-1.75
Click to expand...
R8 and both the old and new drawbars are 7/16-20 threads which match the R8 collets.
 
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