Setting drill stop collars

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fcs

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Rank beginner question here. Making fishing rod ferrules I need to drill &ream holes to semi-precise depths on my little Sherline lathe. Semi-precise is +- 0.005 inch. I’m doing this by stop collars. Setting the collar requires holding the caliper with one hand, the drill and collar with the other and tightening the screw with the third, while peering over the top of my glasses and guessing how close I am. Then usually doing it all over again. There must be a device to do this. Would a vernier depth gauge work? Or some mod of a spare caliper to get the depth right the first time?
 
Sounds like you need to make a two-piece precision stop. One piece is externally threaded and set screws to the drill, the other internally threaded, screws onto the first piece and locks with a soft-tip set-screw. Lock the first piece onto the drill, adjust the second piece by means of the thread and lock to the first piece.

Or something like that.
 
If you have a limited number of depths to set, and you are going to be repeating this work from time to time, make a piece drilled through with the bit in question, and cut to the length of your desired depth. Plunk your bit into it tip down on some flat surface, and then set your depth stop down on top of it.
 
A bit more info would help.
  • Is the hole blind or through? I'm sure you know that you should not bottom a reamer in a blind hole.
  • How many do you need to do? If there are a lot of pieces or a production job then perhaps rigging a drill chuck to a QCTP holder so you can use the cross slide to drill might be worth doing.
  • Would tape on the drill and reamer be precise enough to mark your depth? Depending on your vision, you can use tape to tell you when you're close and use the marks on the handwheel to get within a half thou.
 
For jobs like that I use a micrometer stand.. I fixture the mic in the stand and have 2 free hands to position the stop and secure it.

I just bought a couple of these from Discount Machine. They're the eBay store for Shars tools.

www.ebay.com

PRECISION MICROMETER HOLDER STAND BASE INSPECTION NEW A | eBay

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Before making a purchase I literally looked at hundreds of them. It seems even the high priced ones with the Mitutoyo name look identical and come from the same place
 
mikey said:
A bit more info would help.
  • Is the hole blind or through? I'm sure you know that you should not bottom a reamer in a blind hole.
  • How many do you need to do? If there are a lot of pieces or a production job then perhaps rigging a drill chuck to a QCTP holder so you can use the cross slide to drill might be worth doing.
  • Would tape on the drill and reamer be precise enough to mark your depth? Depending on your vision, you can use tape to tell you when you're close and use the marks on the handwheel to get within a half thou.
Click to expand...
These are blind holes. I’m not sure why I would care about the depth of thru holes? These are one or 2 offs. Then I’m on to a different size and depth. Final hole sizes after reaming are < 0.3 and depths from 0.5 to 1.5 inches. Drilling and reaming require pecking (& clearing the chips with a mascara brush when reaming) this makes counting wheel revolutions error prone at least for me.
I’m leaning toward a vernier depth gauge. I haven’t bought a new tool in over a week.
The micrometer stand looks like it will help. Good idea. Another new tool!
 
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