- Joined
- Oct 30, 2002
- Messages
- 3,974
I recently picked up a new grinder from Brodbeck. Looking through posts over the last several years, I see lots of recommendations for ratcheting tension systems, to the point that some dismiss grinders like the one I purchased because of the shock or spring tension systems. I can definitely see the benefit of a ratcheting system, so I decided to play around with adding one to this grinder.
I had a ratcheting parking brake handle left over from a car build, so I took the cog gear portion of the handle and retrofit it to the grinder tension arm pivot. Then I created a handle to engage or release the teeth and mounted it.
There were two problems with this cobbled together setup. First and foremost, the teeth were too far apart, creating too big of jumps in tension with really only a single sweet spot. Also, I only had a single engagement point on the teeth, which did work for teeth this large but would cause problems with smaller teeth.
So I scrapped the car part and made my own cog gear. The challenge here is that I had to roughly hand-file my own teeth, so they're not the greatest and not entirely synmetrical. I also added multiple engagement teeth on the arm, also not the greatest. However, with twice as many teeth, I have a much greater control over the tension.
Here is where it stands right now (the gas shock isn't engaged, just swing out of the way while I mocked it up):
I need to add a tension spring to keep the arm/teeth engaged and clean things up a bit. Obviously, it would be best if I could heat treat the teeth, but I don't think I'll have much luck with hardening this cheap weld steel.
The absolute best solution would be to have the two parts laser cut with symmetrical teeth out of 1050 or similar so I could harden the teeth somewhat and have a better engagement of the tension arm. I'll have to look into something like that to see if there is someone who could CAD the pieces and cut them for me. Anyway, fun quick project, so I thought I would share.
For completeness sake, here is the whole grinder. It can pivot horizontal, and I have the same accessories I had on my KMG but added their surface grinder attachment. I also have a KMG adjustable work rest on the way. Maybe I'll stop piddling on the roadster for a while and actually make a knife again in the near future. It's been a long while.
I had a ratcheting parking brake handle left over from a car build, so I took the cog gear portion of the handle and retrofit it to the grinder tension arm pivot. Then I created a handle to engage or release the teeth and mounted it.
There were two problems with this cobbled together setup. First and foremost, the teeth were too far apart, creating too big of jumps in tension with really only a single sweet spot. Also, I only had a single engagement point on the teeth, which did work for teeth this large but would cause problems with smaller teeth.
So I scrapped the car part and made my own cog gear. The challenge here is that I had to roughly hand-file my own teeth, so they're not the greatest and not entirely synmetrical. I also added multiple engagement teeth on the arm, also not the greatest. However, with twice as many teeth, I have a much greater control over the tension.
Here is where it stands right now (the gas shock isn't engaged, just swing out of the way while I mocked it up):
I need to add a tension spring to keep the arm/teeth engaged and clean things up a bit. Obviously, it would be best if I could heat treat the teeth, but I don't think I'll have much luck with hardening this cheap weld steel.
The absolute best solution would be to have the two parts laser cut with symmetrical teeth out of 1050 or similar so I could harden the teeth somewhat and have a better engagement of the tension arm. I'll have to look into something like that to see if there is someone who could CAD the pieces and cut them for me. Anyway, fun quick project, so I thought I would share.
For completeness sake, here is the whole grinder. It can pivot horizontal, and I have the same accessories I had on my KMG but added their surface grinder attachment. I also have a KMG adjustable work rest on the way. Maybe I'll stop piddling on the roadster for a while and actually make a knife again in the near future. It's been a long while.
