-
The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details: https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is$300$250 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
Surface grinding attachment WIP
- Thread starter Hubert S.
- Start date
I made hardened inserts from A2 drill rod for the sine bar. The studs are press fit into the base plate, and the little disks are screwed in and secured with red Loctite. I first installed the disk at the 5" distance from the pivot and set it so that the front edge of the top plate was parallel to the front edge of the bottom plate. I let that cure for a while and then installed the disk at the 10" distance. I first screwed the disk in all the way, then bottomed the sine bar out against the first disk and locked it in place. Then, I unscrewed the disk at 10" until it touched the stud and checked with a feeler gauge and back light. This process was a bit fiddly as there is not much to grab onto, but the Knipex parallel pliers worked pretty ok.
I also rounded the corners of the base plate and drilled and tapped mounting holes. The threaded studs are secured in the base plate with red Loctite as well. I got some pretty nice powder coated zinc adjustable levers from McMaster.
I also got the chuck mounted today. It is fastened from the front using five 1/4"-20 bolts. I drilled 17/64" holes and countersunk with a 3/8" endmill. The wheel is just sitting there for the picture, it is not mounted yet. I have to shorten the back side of the shaft a little and drill and tap a hole in the back side. I've been putting it off because the 3-jaw chuck is mounted on the lathe and it is a bit of a pain to take off. I'll get to it next week and then it's time to make some sparks!
I also rounded the corners of the base plate and drilled and tapped mounting holes. The threaded studs are secured in the base plate with red Loctite as well. I got some pretty nice powder coated zinc adjustable levers from McMaster.
I also got the chuck mounted today. It is fastened from the front using five 1/4"-20 bolts. I drilled 17/64" holes and countersunk with a 3/8" endmill. The wheel is just sitting there for the picture, it is not mounted yet. I have to shorten the back side of the shaft a little and drill and tap a hole in the back side. I've been putting it off because the 3-jaw chuck is mounted on the lathe and it is a bit of a pain to take off. I'll get to it next week and then it's time to make some sparks!
I made a little knurled thumb screw to secure the dial indicator today. I drilled and tapped the indicator holder for M3 and then cut it with a slittling saw. The knurled knob is cold blued using JAX. While I was at it, I also cold blued the chuck. This turned out ok, I guess.
I mounted the wheel on the tool arm a couple of days ago using a 1" shaft turned down to 20mm to fit the contact wheel bearings. This is extremely rigid and I cannot measure any flex with my indicator when applying tension to the belt. This setup is far more rigid than any of the wheels I have mounted on 1/2" shafts.
I also took the translation stage apart and eased all sharp corners with a Scotchbrite belt before reassembling with blue Loctite. Made a bit of a mess in the process trying to unclog the nozzle on the almost brand new Loctite bottle. The pop-up cap was stuck and would not budge until I flushed it with acetone. Of course, my hands ended up looking like those of a smurf.
I don't have a handle or stops on the ends yet, but I wanted to try it out so I ground the chuck flat. This took 30 thou on the right side and 34 thou on the left side, which is pretty much the same amount it took to mill the back side of the chuck flat after it had warped. I put a magnet in the center slot of the chuck and measured how much I have left and it came out to just under 70 thou.
Now I have to figure out what to do for a handle, maybe I'll just use a piece of pipe and a bike handle grip.
I mounted the wheel on the tool arm a couple of days ago using a 1" shaft turned down to 20mm to fit the contact wheel bearings. This is extremely rigid and I cannot measure any flex with my indicator when applying tension to the belt. This setup is far more rigid than any of the wheels I have mounted on 1/2" shafts.
I also took the translation stage apart and eased all sharp corners with a Scotchbrite belt before reassembling with blue Loctite. Made a bit of a mess in the process trying to unclog the nozzle on the almost brand new Loctite bottle. The pop-up cap was stuck and would not budge until I flushed it with acetone. Of course, my hands ended up looking like those of a smurf.
I don't have a handle or stops on the ends yet, but I wanted to try it out so I ground the chuck flat. This took 30 thou on the right side and 34 thou on the left side, which is pretty much the same amount it took to mill the back side of the chuck flat after it had warped. I put a magnet in the center slot of the chuck and measured how much I have left and it came out to just under 70 thou.
Now I have to figure out what to do for a handle, maybe I'll just use a piece of pipe and a bike handle grip.
- Joined
- Nov 18, 2009
- Messages
- 198
I use compressed air to clean off my mag chuck. Works fast
I attached a piece of 3/4" T-track to the rail and fabricated a couple of stops. They have a key in the back that fits in the track and are fastened with a 1/4"-20 bolt to a 1/4"-20 jam nut in the track. The stops slide nicely in the track but have almost no play. I put a couple of self adhesive bumpers on the translation stage to cushion the impact. In the picture below, both stops are tight against the stage so the rail cannot move when I take the SGA off the grinder for storage. Aside from a handle, the SGA is now complete.
The two levers that lock the sine bar work well enough as handles for the moment, so I tried it out. I ground a ~7" long piece of mild steel front and back and then measured it with a micrometer in a few places. Aside from the very ends, the variations were less than 0.5 thou. At the end, I measured higher deviations, but all measurements were within one thou. I also ground a couple of AEB-L knife blanks, one honesuki and one gyuto, that I had already heat treated. This works so much better than the old magnet and flat platen routine I have been using so far! I had straightened both blanks with a carbide hammer after heat treat, and both of them picked up a slight warp after grinding the first side. After grinding the second side, one ended up straight, the other still has a slight warp that should be easy to correct. I am pretty excited about how well the SGA works, I think it will be a really useful tool.
The two levers that lock the sine bar work well enough as handles for the moment, so I tried it out. I ground a ~7" long piece of mild steel front and back and then measured it with a micrometer in a few places. Aside from the very ends, the variations were less than 0.5 thou. At the end, I measured higher deviations, but all measurements were within one thou. I also ground a couple of AEB-L knife blanks, one honesuki and one gyuto, that I had already heat treated. This works so much better than the old magnet and flat platen routine I have been using so far! I had straightened both blanks with a carbide hammer after heat treat, and both of them picked up a slight warp after grinding the first side. After grinding the second side, one ended up straight, the other still has a slight warp that should be easy to correct. I am pretty excited about how well the SGA works, I think it will be a really useful tool.
Thanks, Ken, I appreciate it. I already made some modifications to it today, but they were part of the plan. I drilled and counter sunk new mounting holes in the rail today to offset the chuck to the right. This gives a lot more clearance for cleaning and putting long blades on the chuck as you can see in the picture. I initially used the bolt holes that were already in the rail because I wanted to measure the offset after the end stops were in place. I also drilled a mounting hole for the handle at the end of the chuck.
The poor surface finish on the back of the chuck has been bothering me a little bit. When I took out the warp I had forgotten to lock the column and got a lot of chatter, you can clearly see it in the picture. I decided to just forget about it, so I took out the chuck mounting screws one by one and fastened them with Loctite. All that is left to do now is make a handle and bolt it on, and maybe drill a hole at the end of the tool arm so I can hang the whole thing on the wall.
Last edited:
Looks like you've got a 1/2"X20 thread to adjust? That gives .050" per round? AND a nice setup for the dial indicator. I'll be very interested to know when you move the dial indicator, say .010", how much material that will take off. I took my dial indicator off, decided I didn't really need it there and used it elsewhere. Most of my adjustments while grinding are in the .005" range, or even less. Even .005" is a BIG cut for a real surface grinder. Back 50 yrs ago when I ran a surface grinder in a shop .001" was considered a big cut, and sometimes in the tenths of a thou range. Of course the surface grinder was using stone wheels rather than a belt.
The thread is 3/8"-24. I went in 1 thou increments on the hardened steel I ground, but I had a 120 grit belt on there. I did not measure to see how well the dial indicator reading matched the actual material removal yet, but I plan to do that at some point. I'll post results here when I get around to it.
By the way, the plastic bristles on that Nicholson file card you see in the picture above work really well to take the grinding dust of the chuck. Whatever the file card misses comes off with compressed air pretty easily. Now that I've moved the chuck over, I can reach the whole chuck with the file card to clean it up.
Something else I forgot to mention earlier, the whole assembly weighs just shy of 33 lbs. On the way to the scale I thought it carried more like fifty pounds, so I was a bit surprised that it came in so light. Anyway, I think I'll try to find a spot on the wall for it somewhere real close to the grinder...
Yea, I remember you saying the thread was 3/8"-24 from an earlier post now - I'd just forgot. I do a lot of "forgetting" these days 
33 lb? Not that bad for a young man. I've not thought about weighting my assembly. I break it down to the chuck and the tool arm portion for storing.
33 lb? Not that bad for a young man. I've not thought about weighting my assembly. I break it down to the chuck and the tool arm portion for storing.
Ken, I did a test today on a piece of mild steel to see how well the dial indicator reading matched the actual material removal. I used a 120 grit ceramic belt and did two increments of 2.5 thou for a total of 5 thou between measurements. I repeated this four times and took the piece from 0.12" down to 0.1". I only used calipers for this test, but the readings were all spot on.
Good deal on the printed handle. Did you draw that up in Fusion360? I just recently got a 3D printer (Ender 6) and use FreeCAD for drawing projects. I had no idea I'd use the 3D printer as much as I have over the couple of months I've had the printer. I suspect that printed handle will last just fine, and be a LOT less expensive than the size of Micarta would be.
That's a good test - I've never really tested my SGA like that with 120 grit, only with 36 or 50 grit and that's pretty large grit for accurate testing. For each .005" moved in, I'd get maybe .003" or so removed. I do have a fairly soft wheel which would make a difference, and taking light cuts rather than "hogging" would also help the accuracy on removing material.
That's a good test - I've never really tested my SGA like that with 120 grit, only with 36 or 50 grit and that's pretty large grit for accurate testing. For each .005" moved in, I'd get maybe .003" or so removed. I do have a fairly soft wheel which would make a difference, and taking light cuts rather than "hogging" would also help the accuracy on removing material.
3D printers are really nice for prototyping. I suspect the printed handle will be on there for a while, I want to make some knives before spending more time on the SGA. I don't use Fusion 360, I never really learned CAD. We still did all drawings by hand when I went through school. I tend to use a program called OpenSCAD where you define shapes and add/subtract them from each other to arrive at your final model. All this is done via a text file, which I edit using Emacs. For the handle, I cheated a bit and drew the cross section in Inkscape and then simply extruded it in OpenSCAD.
OpenSCAD huh? That's a tough program to draw in. I've played with it a little, using it mostly for using an existing file that has parameters where I can change things as I need them. For drawing from scratch FreeCAD is MUCH easier for me. I understand it has some similar to Fusion.
Yep, in school and for the first few years of engineering work I drew by hand also. Quickly decided CAD was better, and been using AutoCAD since 1988. Boy have computers changed since then
Yep, in school and for the first few years of engineering work I drew by hand also. Quickly decided CAD was better, and been using AutoCAD since 1988. Boy have computers changed since then