Home Machine Shop Tool Making - Machining A Pinion Head Depthing Tool - Part 1

2017-10-25 1

Machining A Pinion Head Depthing Tool, Part 1, by Clickspring.\r
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In this firstof a 3 partI start the depthing tool project by making the bed for the tool, as well as the carrier bolts.\r
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Plenty of lathe work, milling, drilling and use of a Vertex rotary table with a shop made fixture plate (based on Frank Fords design)\r
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Im following WR Smiths design for the depthing tool. You can find plans and a description for it in his book Clockmaking and Modelmaking Tools and Techniques (link below).\r
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For more info on this build, as well as other tool making info and plans, visit the blog site at \r
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If you would like to help support the creation of these videos, then head on over to the Clickspring Patreon page: \r
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Other Videos to Watch:\r
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How To Make A Clock In The Home Machine Shop - Part 5 - Cutting The Pinions\r
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Home Machine Shop Tool Making - Machining A Tailstock Die Holder For The Sherline Lathe - Part 2\r
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Transcript:\r
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00:19 A few of years ago I met a retired clockmaker who sold me a lot of his tools, and one of the things I picked up from him was this depthing tool. \r
If you need to depth wheels and pinions that are already fixed on their arbors, or maybe made from a pinion wire, then this is the tool youd need. So thats what this 3 partis all about; building one of these simpler pinion head depthing tools.\r
01:03 And when in place, they accept runners, that with simple bushings,as temporary arbors on which wheels, pinions and even escapements can be mounted to perform the task of depthing.\r
01:48 I cut off a piece of stock, and started the job by squaring it up on the mill. And then I found the edge and using the DRO, located and drilled the end holes that will define the central slot.\r
02:02 I used an undersize slot drill to roughly open up the slot first and you can see Im taking pretty shallow cuts, just nibbling away at it really.\r
02:31 My mill is quite light duty. I can get good results from it, but I do need to nurse it along when cutting slots. That took care of the bulk of the metal that needed to be removed.\r
03:15 The adjustment screw is supposed to run right down the center of the slot, and it will really stand out, if its not right down the middle, so I took quite a bit of care positioning and clamping the work for the next step. The top end was then drilled and tapped for that screw.\r
03:49 And at this point I nearly got myself into a bit of trouble. Im using a carbon steel tap here, and it was a mistake; the tool steel is just too tough for it. I could feel the tap was right on the edge of snapping off with every turn; not a nice feeling!\r
04:13 That extra bit of time spent on the setup was worth it; the thread came out right down the middle. This is my version of Frank Fords rotary sub table. Ive put a link to it in the description box below.\r
04:41 the table axis. and best of all, theres plenty of room on the table for dowel pins and clamps to hold everything down. It took a bit of time to make, but Its made the table so much more usable.\r
05:36 The 2 carrier bolts were made next, and these are probably the most difficult parts to make in terms of accuracy. The underside and top surfaces need to be perfectly true to each\r
05:45 other, and perpendicular to the bore for the tool to work correctly. So this part will need to be finished between centers. But a lot of it can be roughed out first, and some of the features machined before that happens.\r
07:19 When the tool is in use, the set screw will hold the runners in place. But its going to come in very handy in a moment, to help finish off the part.\r
08:04 And heres why that set screw is so helpful: I can use it to mount the part onto this little arbor for the next operation. With the part running on its bore between centers,\r
09:09 The result of all of this between centers operation, is that those two flat surfaces that are critical to the tools accuracy, are now true with each other, and also perpendicular to the bore.\r
09:48 And thats the carrier bolts done. In the next video Ill make the knurled carrier nuts and the adjustment screw\r
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References:\r
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WR Smith workshop and clock construction books:\r
Plans for WR Smith Depthing Tool\r
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Frank Ford Rotary Table Fixture Plate:\r
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John Wilding workshop and clock construction books: \r
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Machining A Pinion Head Depthing Tool, Part 1, by Clickspring.