Lathe Tool & Drill Bit Sharpening
Host Tool Craft & Neil Butterfield
December 4th 2004
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Members in Attendance
The meeting was held at ToolCraft and as always we thank Bob Sanders and crew for allowing us to invade!
The meeting convened at 9am with a large number of members and grinders in attendance. Pictured left to right: Glen Lynch, Robert Reisman, Dale Schmidt, Scott Brown, Tom Davis, David Butterfield, Gene Lucas, Doug Endrud, Bill VanOrden, Lance Greathouse and Jerry Hine.
Neil starts out the session describing the advantages of using that old lantern type tool post and holders. The general consensus of the machinists in the group was carbide had little use in the home shop. Carbide requires a heavy cut and associated higher HP requirements to cut effectively. HSS (high speed steel) was suggested to be the tooling material for the home machinist. HSS tools with a higher cobalt content could also be used but it was suggested that this was not needed. For users of the insert type tool holders, Neil suggested HSS inserts over carbide.
Neil diagrams the various angles suggested for lathe tool bits when working with HSS. We spent quite a good bit of time discussing the reasoning behind the angles incorporated into different tools. Specifically our example the right handed lathe bit. We covered roughing and finishing and the radii incorporated into different bits for both processes. Some discussion of specialty bit making was covered. Using oil hardening stock to make form tools and re-harden them. This was covered in detail in a previous meeting this year. There are those pesky doughnuts again....
Neil's diagrams. These were on a few sheets given out in "class".
Nothing's better than a well dressed wheel. The use of the dresser was discussed. The dresser is doing it's job correctly when there are minimal sparks and a modest amount of dust coming off the wheel. It was pointed out that the feet on the dresser are actually there to hook over the tool rest to get the proper pressure and angle when dressing the wheel. Further discussion of the wheels centered on type and mounting. It was pointed out that the paper labels on the wheels must be used, the cushioning of the paper helps keep the wheel from fracturing. jerry Hine also made a good point that you should stand to the side of the wheel when starting up the grinder just in case the wheel has been damaged prior to it's use for the session. This is also a good practice at anytime, but especially when installing a new wheel.
Lathe tool grinding then commenced. Neil demonstrated how to grind our example the right handed cutting tool. It was pointed out that you need to keep the tool bit relatively cool when grinding. As long as you can hold it in your hand without burning and dip it regularly in the water cup you should have no problems with changing the hardness of the cutter. It was suggested that the tool bit be deburred with a diamond hone. Woodcraft (Elliot Rd & Arizona Ave) has a nicely priced set of three. Medium, Fine & Super Fine, # 141515 for $19.00 NEW
Members brought a variety of grinders and they were set up for use. The large machine to the left in this picture is a wet wheel tool grinder specifically made for tool bit sharpening. The blue grinder in the back is a low speed (1750 RPM) grinder of the type sold at woodworking stores for wood tool sharpening.
Notes were taken (Scott Brown), information was exchanged. Gene Lucas and Jerry Hine are to the right of Scott, Dale Schmidt at right is part of another group discussion.
Neil demonstrates, using the turned off grinder, a means of aligning the cutter tip on a lathe during setup. You place a straight piece of metal strip between the cutter tip and the part being turned. If the strip remains at right angles to the work piece and cutter tip, the tip is at the centerline of the work piece. If the top of the strip tips away from the operator the tip of the cutter is above the centerline and conversely tipping towards the operator it is below centerline.
Bob Sanders held court on hand drill bit sharpening. Here members of the group listen to suggestions on relief angles, point shape and other details of the bit.
The drill angle gauge was used and discussed. This is one sure way to get the tip angles correct to prevent uneven cutting and bit wandering.
Bob has at the grinder with a drill bit after explaining the proper angles and movements to hold the bit when hand sharpening. He made it look sooo easy!
The results of Bob's hand sharpening were tested in the drill press up front, and as expected it worked just fine.
(both - Marty Escarcega)
The Drill Doctor made by Darex was discussed. A number of members have had less than satisfactory results using it. Beevo (aka Bill VanOrden) happened to have his in the car and brought it in and offered to by any Drill Doctor for $25 cash. Since there were no takers he then demonstrated how to make it work and get good results. Other members tried their hand at sharpening drill bits on this tool. It was mentioned that the instructional video tape that comes with the tool must be viewed to be successful when using this little tool.
Keeping all this in mind it was determined that for most of us home shop guys, when you break a bit on Sunday morning and you need to get this project done, just sharpen what have with the wheel you have and get back to making chips. With 5 grinders handy everybody got a chance to give it a try. Everybody learned something and swapped tricks, it was nice to see everyone getting some hands on.
Show & Tell
A few projects were brought to the meeting.
Robert Reisman brought a couple of engines he has made. The small hit & miss engine was made from castings obtained over the web. He ran it for a while before the meeting started. The 5 cylinder radial was made from metal stock using the series of articles in the Home Shop Machinist magazine. The little radial runs on compressed air and the only store bought part was the propeller. Robert took the time to explain that he built these to understand how they work and not just how to build them. It was stated that this was as fun as building them in the first place.
Beevo brought a newly completed parallelogram binocular mount he made for his wife Earla. The purchase of a larger pair of binoculars dictated some sort of support as these Celestron 25X100's weigh around 10 pounds! The benefits of the parallelogram mount is the height of the binoculars can be adjusted without the object moving in the field of view. The end of the rod has two 5lb barbell weights to counter balance the binoculars. All aluminum construction, it contained his first rotary table made part, the sector plate below the binoculars them selves.
Thanks guys for bringing these in to show the group. I personally enjoy seeing what everybody else is up to and find it a source of inspiration and I believe the group does also.
Except where noted all images by Bill VanOrden