Home Built Surface Grinder

The wavy surface might be partly due to slight eccentricity in your contact wheel. I trued up my contact wheel using a flat piece of steel with some sandpaper attached with spray glue. I posted a thread about it here:

Truing up an SGA contact wheel

I just built a surface grinding attachment and noticed some slight waviness in the surface finish of the test pieces I ground. The amplitude of the waves is very small and barely makes the needle on my test indicator move, but it is pretty visible by eye, even though it is very difficult to...
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As I'm sure you're aware using a firm wheel helps, perhaps even an aluminum wheel that's precision turned. Also shallow passes for finish work, perhaps only .002" or so deep. You should be able to get <.001" over the 150mm lenigth. Here is one of my best results showing what it can do;
Tang.jpg

Middle.jpg

Tip.jpg


Darn, those images are larger than planned. AND do remember, this is about the best I've done - usually more like .001" to .002" over that 10" length
 
I've had issues with loosness in that table slide. I ended up wedging in some 0.010'' shims to tighten everything up... not ideal, but it got the job done.

I hope someone finds a better option for this cross table one day. I was even thinking of buying a cheap mill vise and modifying it.
 
jeness said:
Thanks! Looks like a good starting point to address the waves in the finish.
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If you don t want waves in the finish , get real surface grinder .Very light pass at finishing will help a lot .Slow moving chuck also would help , but you will see them there whatever you do ......problem is that belt is not endless ,it is glued at the ends :)
 
J. Keeton said:
I hope someone finds a better option for this cross table one day. I was even thinking of buying a cheap mill vise and modifying it.
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I made my own dovetail slide with adjustable gib screws on the mini mill, see link below. There are other DIY solutions that are a bit easier/quicker to machine documented in this thread, and I think K Ken H> posted his version in a separate thread as well, but it's been a minute since I looked at all of this.

Surface grinding attachment WIP

I started building a surface grinding attachment and thought I would document my progress as I go along. This build is likely going to take a little while, as I have not really made a plan or ordered any components other than the linear rail. My first step was to make the chuck. I am not sure...
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Reviving an old thread here I guess, but it's such a good one! Let me know if this should go in a different thread.

https://imgur.com/a/CdzLqGP

I am designing my own SGA, like many of you, and had a couple questions for the hive. First, my current SGA design has the centerplane of the chuck an inch too far from the centerplane of my tracking wheel. I was wondering if it would be fine to put a spacer that thick to offset it. Off the top of my head, it sounds like a spacer that thick might make the thing a little unsteady, to put it out that far from the tool arm. Do you all agree? Is there some other suggestion to mediate this? I'm not really fond of the idea of slimming down the SGA, its exactly as sturdy as I would want it.

Second (and this kinda ties in with the first point), I am going to be using a 3" wide wheel on the SGA, while my tracking wheel is 2.25" wide. Should the centre planes of both wheels be aligned, or would it be ok to ride the belt a 1/2" or so off the edge of the tracking wheel when this attachment is in use? Would it be better to switch my tracking and drive wheels to 3" wide ones?
 
Hey there Levi. Welcome to blade forums. Looks like you're on track with design.

I'm not sure about the chuck spacing, it would really depend on where you did it (or in the arm or the chuck mount). I'll say for a while, I used some 3x3 angle iron as the chuck on my sga, and it did feel more stable when I switched to the solid piece of aluminum that most folks use. There's a guy named Dennis Tyrell who makes them, if you don't have a mill. I think I'd start with that, and then design the rest of the attachment around it.

As to the wheel alignment, I'd start with aligning them to the center of both wheels, and then run off if you need more (this is what I did when I had a 2.5" chuck). Since I got the pre made 2" chuck from Tyrell, I haven't had to do this, and I personally haven't missed the extra .5", but your milage may vary. Switch to 3 inch wheels and the appropriate sized chuck if you think you'll be needing the extra real estate.
 
N.W. Gean said:
Hey there Levi. Welcome to blade forums. Looks like you're on track with design.

I'm not sure about the chuck spacing, it would really depend on where you did it (or in the arm or the chuck mount). I'll say for a while, I used some 3x3 angle iron as the chuck on my sga, and it did feel more stable when I switched to the solid piece of aluminum that most folks use. There's a guy named Dennis Tyrell who makes them, if you don't have a mill. I think I'd start with that, and then design the rest of the attachment around it.

As to the wheel alignment, I'd start with aligning them to the center of both wheels, and then run off if you need more (this is what I did when I had a 2.5" chuck). Since I got the pre made 2" chuck from Tyrell, I haven't had to do this, and I personally haven't missed the extra .5", but your milage may vary. Switch to 3 inch wheels and the appropriate sized chuck if you think you'll be needing the extra real estate.
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Thanks for the speedy reply. I will be doing the machining myself, and the chuck is 3" wide to accomodate the mounting of the switchable magnets I have. You can see the picture I attached in my original post, the chuck isn't slotted for permanent magnets like most on here (are you able to see the image?). I couldn't really think of a way to design the rest of the attachment to align the chuck with my wheels, other than putting that thick spacer, so I was hoping (desperately) someone on here might chime in with a new perspective on that, or maybe someone that has used a spacer that thick and it worked.
 
Really good looking design so far.

At this stage if I were you I would figure out how to get the centerline of the chuck on the same plane as the centerline of all of you pulleys. This would just be the proper thing to do and with the amount of work that will go into building this you may regret it if it has to ride off center all the time. I wouldn't be afraid to try a 1 inch spacer.

Also I would suggest making the top, working surface of your chuck slightly under 2 inches that way you can dress the entire surface with a 2 inch wide belt. You will want to do this to get the chuck square with the pulley. What I did on my SGA chuck was just put a step in on the sides since I also needed it to be wider that 2 inches. You can see what I am referring to in this picture:


SGA+2.png


Also, I would highly suggest to anyone running a SGA to use a steel pulley.
 
Has anyone made the chuck with electric door mag locks? I think there would be enough meat to dress and square them up to the pulley?
 
I think one of the BF members has a surface grinder attachment with electro-mags. Contender????

We often use electric door magnets on the doors in the jewelry business. I can attest that they are so strong you cannot pull or push the door open until the magnet is turned off.
I have one somewhere in the shop. I'll have to find it and do some testing for the surface grinder. Besides easy release, it would make cleanup of the grinding dust and swarf much simpler.
 
I picked up one recently (600#, flush mount), but haven't tried it. Trying to figure out the mounting part, but it seems pretty solid. It would be much less expensive than using the MagSwitch magnets, too (600# are around $30 each and 10" long, so 2 would like $60 and around 20" surface).
 
IIRC, mine is a 1200# pull. I was thinking of using it for small blades. I don't think the magnet plate is more than 4".
Be aware that the listed ratings may vary a lot from actual force (part hype and part just plain a lie). I consider the listed power rating like shop vacs that say they are 5hp but draw only 3 amps.
Alignment and spacing make a huge difference in applied force. For us, the blade needs to sit flush to the magnet plate.
Also, while your unit may be 10" long, the magnet plate may only be 3 or 4 inches long. In your 20" setup, that may leave an unmagnified space between the two units that could be 4 to 6 inches. On a thinner blade stock this might actually warp the blade while grinding. Play with it and let us know how it goes.
 
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Yeah, the magnet plate is like 6 or 7" long IIRC on the one I have and the wings are around 1.5" long or so. Other ones (non flush mount) have one end with unsupported area and the mag area goes almost to the end on the other side. I may need to shim the gap area between the 2 units; I can coat with JB weld and then grind it flat when I square up the chuck to the contact wheel. That way the JB weld will fill any gaps.

I want to power mine up and try it on the belt sander and see if the blade slides at all.
 
Taz said:
Has anyone made the chuck with electric door mag locks? I think there would be enough meat to dress and square them up to the pulley?
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I have one. I think I even posted a pic some time ago...
wH4DC7P.jpeg

Since then I have abandoned this mounting system with standoffs, and I have mounted it directly to the slide. I do dress it from time to time but trying not to overdo it. Works ok for me.
 
Contender Machine said:
Really good looking design so far.

At this stage if I were you I would figure out how to get the centerline of the chuck on the same plane as the centerline of all of you pulleys. This would just be the proper thing to do and with the amount of work that will go into building this you may regret it if it has to ride off center all the time. I wouldn't be afraid to try a 1 inch spacer.

Also I would suggest making the top, working surface of your chuck slightly under 2 inches that way you can dress the entire surface with a 2 inch wide belt. You will want to do this to get the chuck square with the pulley. What I did on my SGA chuck was just put a step in on the sides since I also needed it to be wider that 2 inches. You can see what I am referring to in this picture:


SGA+2.png


Also, I would highly suggest to anyone running a SGA to use a steel pulley.
Click to expand...
Thank you! I will put that step in my chuck design. I will be using this for alot of 2.5" wide blades though, so you think it's fine if the whole thing isn't against a trued surface? Maybe 3" belts are a thing. Also, it looks like the arm on yours has a step on one side? Was that arm milled down on one side? It might be worth it for me to simply get a 2.5 x 1.5 bar of aluminum and mill it down to have the 1" offset built into the solid piece. Expensive though lol. Maybe a steel arm would be better for that.
 
Levi Prince said:
Thank you! I will put that step in my chuck design. I will be using this for alot of 2.5" wide blades though, so you think it's fine if the whole thing isn't against a trued surface? Maybe 3" belts are a thing. Also, it looks like the arm on yours has a step on one side? Was that arm milled down on one side? It might be worth it for me to simply get a 2.5 x 1.5 bar of aluminum and mill it down to have the 1" offset built into the solid piece. Expensive though lol. Maybe a steel arm would be better for that.
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My design uses 2 arms for the SGA to mount to and a third arm for the wheel to mount. The 2 arms are very simple in that they each have two mount holes. The SGA assembly has a heavy main plate that the rest of the guides etc mount to. This is how I got it to drop down and line up with the center of the pulleys. I am not sure if 3 inch wide belts are available but I wouldn't be afraid to grind a 2.5 inch wide blade on mine. It wouldn't be fast because I would have to track the belt back and forth to cover the whole blade but it would work. I also made the mounts for my chuck adjustable so I can move the entire chuck off center about an inch if I remember correctly.

Stacy E. Apelt - Bladesmith Stacy E. Apelt - Bladesmith - The chuck I make and sell is not electric. It is a design of my own that is closer to a traditional on/off permanent magnetic chuck. In the off position it had no magnetic pull but an already magnetized blade will stick just enough to support its own weight. This is very handy in that you can fine tune the placement of the blade on the chuck without having it fall on the floor.
 
Contender Machine said:
My design uses 2 arms for the SGA to mount to and a third arm for the wheel to mount. The 2 arms are very simple in that they each have two mount holes. The SGA assembly has a heavy main plate that the rest of the guides etc mount to. This is how I got it to drop down and line up with the center of the pulleys. I am not sure if 3 inch wide belts are available but I wouldn't be afraid to grind a 2.5 inch wide blade on mine. It wouldn't be fast because I would have to track the belt back and forth to cover the whole blade but it would work. I also made the mounts for my chuck adjustable so I can move the entire chuck off center about an inch if I remember correctly.

Stacy E. Apelt - Bladesmith Stacy E. Apelt - Bladesmith - The chuck I make and sell is not electric. It is a design of my own that is closer to a traditional on/off permanent magnetic chuck. In the off position it had no magnetic pull but an already magnetized blade will stick just enough to support its own weight. This is very handy in that you can fine tune the placement of the blade on the chuck without having it fall on the floor.
Click to expand...
Ok, so a 2 arm dealio. Is that because it is too bulky to be supported by just 1? Mine looks like its gonna come in around 35 pounds with hardware and everything. Would it be possible to get some pictures of how that was all mounted, and the step downs on the arms?
 
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