Surface Grinder attachment contact wheel material
- Thread starter BobbyD
- Start date
EdCaffreyMS
"The Montana Bladesmith"
Neither! Either of those will be too soft, and will result in a convex face on whatever you're surface grinding. The down pressure causes the wheel material to "cup", and creates a convex face on whatever you grind. Can it be avoided with wheels that soft? Yes, but most people don't have the patience to take several passes, to remove .005" of material.
Personally, I use a urethane wheel, serrated, that is the equivalent of 100 durometer on my surface grinder.. and even then, trying to take too big of a "bite" on a pass, will result in a slightly convex surface.
Some of the best performing wheels, in terms of making/keeping the surface of the piece being ground flat and true, are solid wheels made of steel or aluminum. They are very unforgiving in the sense that they will not absorb bumps and lumps in a piece being ground, but if used correctly, you will not find a wheel that will produce a flatter, truer surface. As with most things we do, or most machines we use...there is a "give-n-take"..... it's dealer's choice on what you feel you can give up, to gain what you want. The ultimate goal of surface grinding anything, is to achieve the flattest, truest surface you can...... so whatever it takes to achieve that.... would be the way to go in my opinion.
The "compromise" wheel for me is the urethane I mentioned previously. My original came from South Africa, but I have also had the same wheel made by SunRay Corp. (search for SunRay contact wheels. Their a govt contractor, who make urethane wheels for tank tracks, but also make contact wheels "on the side". They have a few common ones, but most are strictly custom/made to order. They are very good, honest people...just be prepared for a 4-6 weeks wait, depending on their backlog)
Personally, I use a urethane wheel, serrated, that is the equivalent of 100 durometer on my surface grinder.. and even then, trying to take too big of a "bite" on a pass, will result in a slightly convex surface.
Some of the best performing wheels, in terms of making/keeping the surface of the piece being ground flat and true, are solid wheels made of steel or aluminum. They are very unforgiving in the sense that they will not absorb bumps and lumps in a piece being ground, but if used correctly, you will not find a wheel that will produce a flatter, truer surface. As with most things we do, or most machines we use...there is a "give-n-take"..... it's dealer's choice on what you feel you can give up, to gain what you want. The ultimate goal of surface grinding anything, is to achieve the flattest, truest surface you can...... so whatever it takes to achieve that.... would be the way to go in my opinion.
The "compromise" wheel for me is the urethane I mentioned previously. My original came from South Africa, but I have also had the same wheel made by SunRay Corp. (search for SunRay contact wheels. Their a govt contractor, who make urethane wheels for tank tracks, but also make contact wheels "on the side". They have a few common ones, but most are strictly custom/made to order. They are very good, honest people...just be prepared for a 4-6 weeks wait, depending on their backlog)
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Smallshop
KNIFE MAKER
Gold Ed...Thank you.Neither! Either of those will all too often result in a convex face on whatever you're surface grinding. The down pressure causes the wheel material to "cup", and creates a convex face on whatever you grind. Can it be avoided with wheels that soft? Yes, but most people don't have the patience to take several passes, to remove .005" of material.
Personally, I use a urethane wheel, serrated, that is the equivalent of 100 durometer on my surface grinder.. and even then, trying to take too big of a "bite" on a pass, will result in a slightly convex surface.
Some of the best performing wheels, in terms of making/keeping the surface of the piece being ground flat and true, are solid wheels made of steel or aluminum. They are very unforgiving in the sense that they will not absorb bumps and lumps in a piece being ground, but if used correctly, you will not find a wheel that will produce a flatter, truer surface. As with most things we do, or most machines we use...there is a "give-n-take"..... it's dealer's choice on what you feel you can give up, to gain what you want. The ultimate goal of surface grinding anything, is to achieve the flattest, truest surface you can...... so whatever it takes to achieve that.... would be the way to go in my opinion.
The "compromise" wheel for me is the urethane I mentioned previously. My original came from South Africa, but I have also had the same wheel made by SunRay Corp. (search for SunRay contact wheels. Their a govt contractor, who make urethane wheels for tank tracks, but also make contact wheels "on the side". They have a few common ones, but most are strictly custom/made to order. They are very good, honest people...just be prepared for a 4-6 weeks wait, depending on their backlog)
REK Knives
Well-Known Member
The only wheel I've had used by another knife maker that successfully gets the blade perfectly flat is a metal wheel since it doesn't have any give at all. The rubber wheels will allow for some runout at the ends and around the holes in my experience
EdCaffreyMS
"The Montana Bladesmith"
That's a trait of using certain Trizact belts in a surface grinding scenario. As you travel the road of knifemaking, you will find all kinds of little bumps and potholes like that. Generally in the areas you'd least expect.
EdCaffreyMS
"The Montana Bladesmith"
Stuff like that can have several possibilities..... When on a single side like that, it's usually indicative of a misalignment issue.....the belt(s) are pulling/digging in harder on that edge. I've also see that happen when too soft a contact wheel is used, along with too much down pressure applied in a surface grinding scenario, and the belt joint causes the scalloping stuff.
I assume we are still dealing with surface grinder application here? If so, that's another reason you want as hard a wheel as possible for the application.
I assume we are still dealing with surface grinder application here? If so, that's another reason you want as hard a wheel as possible for the application.
BobbyD
Well-Known Member
Yes still surface grinding. So I ground in the chuck. Not sure how that was done before if received it. Put the scallops on the bottom. Seems to have improved. Got a real nice finish with a 120 grit. Tried a 220 grit that I sanded seam smooth which worked good on the flat platen. But it shows the belt bump on the blade. I guess I need some more trizact belts.
EdCaffreyMS
"The Montana Bladesmith"
If you're getting those "belt bump" (kind of a scalloped look) on anything you're grinding, then you're moving the material too fast. On your last couple of passes, go VERY slowly, and you won't have those when you're done. It seems counterintuitive, but it works.