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- Nov 5, 2016
- Messages
- 1,418
Since I finished up installing the 3 phase motor and VFD on my Rhodes shaper, I was looking for a project to do on it and came up with this. A small size (1-5/16" cubed) impossible dovetail puzzle. I used this size since it was the only size I could make from the brass and aluminum material I had on hand. To get the double parallel dovetails to come out right I had to go with a steep dovetail angle. I used 75 degrees. This is where the shaper really shines because you can make any angle you want.
I've seen posts and videos where others have made these on milling machines, using a dovetail cutter, even if the cutter was homemade i.e. Clickspring, but I've never seen where someone has done it using a shaper to cut the dovetails. Oh, I'm sure I'm not the first, but I've just never seen it.
Anyways, using a dovetail cutter on a mill, especially with a DRO, is pretty straight forward since the dovetails are located using the DRO and the cutter cuts the dovetail to size. Even if you offset to take finishing passes with the cutter you can still use your DRO. This is not the case with the shaper, so I developed a plan. I used my Bridgeport to square up the stock and then very accurately, using my DRO, rough out the dovetail slots with an end mill being very careful with proper location and sizes so I could use the sides of these slots for measuring both the location and size of the dovetails when cutting them with my shaper. This was a very tedious operation on the shaper, but it proved to work and work well. Lots of measuring... using mics, depth mics, gauge pins, an anvil mic and dowel pins.
I only shot for two thousands clearance so the joints were nice and tight. One issue I had was with the magnets. I ordered some N35 6mm diameter rare earths from eBay. These babies turned out to be too strong! I tried turning long, small diameter ends on the locking pin, but the magnets still held tight. I'm glad I thought to test this without assembling the two halves or I would have ended up scraping the pieces! I ended up drilling a through hole in the pin and driving in a tooth pick. Using that sticking out about 3/16" on each end did the trick. I will probably replace this with brass or aluminum rod but the tooth pick was a quick and dirty thing to try just to see if the concept would work and it did.
I didn't spend much time polishing this, because I'm sure it will be beat up by friends and family playing with it! Fun project!
I used a matching set of precision V blocks to hold the pieces at the required 45 degree angle. I rough aligned on center by finding the corners with an edge finder. This worked surprisingly well and I only had minimal tweaking to do while sweeping the four sides with my indicator.
I made careful work of both the sizing and location for the slots since these were used with dowel pins to locate and size the dovetails on the shaper.
I used a precision ground 15 degree angle gauge to correctly set the required 75 degree angle on the work head.
The finish product. I hated to have to break all the edges of the dovetails because they turned out so tight and it looked nice. But, safety ruled. I certainly didn't want anyone to win the prize of cutting their finger if they figure out how to open it. They were like razor blades when I got done on the shaper.
This was a great exercise in patience! The shaper is very, very, slow work. But, I had a lot of fun!
Ted
I've seen posts and videos where others have made these on milling machines, using a dovetail cutter, even if the cutter was homemade i.e. Clickspring, but I've never seen where someone has done it using a shaper to cut the dovetails. Oh, I'm sure I'm not the first, but I've just never seen it.
Anyways, using a dovetail cutter on a mill, especially with a DRO, is pretty straight forward since the dovetails are located using the DRO and the cutter cuts the dovetail to size. Even if you offset to take finishing passes with the cutter you can still use your DRO. This is not the case with the shaper, so I developed a plan. I used my Bridgeport to square up the stock and then very accurately, using my DRO, rough out the dovetail slots with an end mill being very careful with proper location and sizes so I could use the sides of these slots for measuring both the location and size of the dovetails when cutting them with my shaper. This was a very tedious operation on the shaper, but it proved to work and work well. Lots of measuring... using mics, depth mics, gauge pins, an anvil mic and dowel pins.
I only shot for two thousands clearance so the joints were nice and tight. One issue I had was with the magnets. I ordered some N35 6mm diameter rare earths from eBay. These babies turned out to be too strong! I tried turning long, small diameter ends on the locking pin, but the magnets still held tight. I'm glad I thought to test this without assembling the two halves or I would have ended up scraping the pieces! I ended up drilling a through hole in the pin and driving in a tooth pick. Using that sticking out about 3/16" on each end did the trick. I will probably replace this with brass or aluminum rod but the tooth pick was a quick and dirty thing to try just to see if the concept would work and it did.
I didn't spend much time polishing this, because I'm sure it will be beat up by friends and family playing with it! Fun project!
I used a matching set of precision V blocks to hold the pieces at the required 45 degree angle. I rough aligned on center by finding the corners with an edge finder. This worked surprisingly well and I only had minimal tweaking to do while sweeping the four sides with my indicator.
I made careful work of both the sizing and location for the slots since these were used with dowel pins to locate and size the dovetails on the shaper.
I used a precision ground 15 degree angle gauge to correctly set the required 75 degree angle on the work head.
The finish product. I hated to have to break all the edges of the dovetails because they turned out so tight and it looked nice. But, safety ruled. I certainly didn't want anyone to win the prize of cutting their finger if they figure out how to open it. They were like razor blades when I got done on the shaper.
This was a great exercise in patience! The shaper is very, very, slow work. But, I had a lot of fun!
Ted