Home Built Surface Grinder

Thank you. My chuck is quite a thick chunk of aluminum. If it doesn't work out, I'll pop the magnets out and have the local shop mill the pockets deeper.
 
Have you guys seen the new Black Fox surface grinder? It's using passive magnet switching for the chuck. You can see the preorder here https://blackfoxknifeworks.com/knifegrinder/black-fox-glide-surface-grinder, and it looks like the magnets are from https://www.kjmagnetics.com/blog.asp?p=magswitch.

They are rather cheap at only $34.95: https://www.kjmagnetics.com/proddetail.asp?prod=MJ-150.

I don't know if the implementation of the magnets is versatile. You can't load up smaller parts across the chuck and surface everything together. For example, multiple sets of slipjoint blades and backsprings.
 
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bmilleker said:
Have you guys seen the new Black Fox surface grinder? It's using passive magnet switching for the chuck. You can see the preorder here https://blackfoxknifeworks.com/knifegrinder/black-fox-glide-surface-grinder, and it looks like the magnets are from https://www.kjmagnetics.com/blog.asp?p=magswitch.

They are rather cheap at only $34.95: https://www.kjmagnetics.com/proddetail.asp?prod=MJ-150.

I don't know if the implementation of the magnets is versatile. You can't load up smaller parts across the chuck and surface everything together. For example, multiple sets of slipjoint blades and backsprings.
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The magnets look pretty cool the only thing it, they would need to be very close to the work piece, ideally touching it. It would be a matter of using an aluminum bar that is slightly thicker than the magnet mount depth to allow for surfacing. you would also need to be able to make the hole in that bar for the magnet. Preferably square.
 
How’s the finish your all getting with these builds? Is it good for just getting the steel quite flat, or are you able to put a final finish on the flats with it? If so or not, what type of belts are you finishing with?
Pictures of your finish would be great also :)
 
I will usually take it to 120. I expect during other operations I will ding flats. I certainly could use it to do finish flats, but I only have one grinder so I don't want to remount the SGA.
 
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KNelson said:
Anyone see why this x axis mount wouldn’t work? It only has 1” of travel compared to the 2” posted way back.. the other one posted is not available right now through the link but is $125 on eBay. I found this one that is similar and USA built..
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I do like the looks of that setup - the 1" of travel isn't a problem at all. The 2"X2" pad on top is smaller than I'd like, but if strong/rigid enough should work.
 
Ken H> said:
I do like the looks of that setup - the 1" of travel isn't a problem at all. The 2"X2" pad on top is smaller than I'd like, but if strong/rigid enough should work.
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Out for delivery today so I’ll know tonight haha. I’ll have to post back with how it works out. All parts are on order, soon to start assembling.
 
My SGA progress. 3" belts and a couple more pieces came today. I need to fix up the plate where the SGA components are attached. I had it at a 45-degree angle from the tooling arm, with the center of the linear table at the axis of the contact wheel. But, the chuck hit my bench in this configuration. I adjusted the angle of the plate to where the chuck was cleared of the bench, but now the table isn't in center with the axis of the contact wheel. Small change to fix up.

I haven't adjusted the linear table yet to try and remove the play. That is a lower priority as I'm confident I can get the tiny bit of play out of it.

51458405_123217592070815_5450710889497290341_n.jpg
 
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My SGA is "finished". I surfaced the chuck last night, and quickly tested on some scrap steel. For not knowing what I am doing, and feeding too much per pass, it appears to be working well. Each measurement I took was within 0.001" to 0.003" of each other. After the test piece, I surfaced the chuck again, to just skim the surface and try and to dial it in even more. I haven't tested on a piece yet, but I am confident the numbers will be even better.

I am using 20 N42 magnets which are supposed to have a hold power of 33lbs each. I am certain the seller didn't send me N42's, but something much lower. I am going to order N52 from a more reputable source, and make a new chuck. My current chuck will work for now, but the test piece I was using was slipping down the chuck when I fed the table too much.

The linear feed table that is receiving bad reviews in here, https://www.aliexpress.com/item/PT-...714.html?spm=a2g0s.9042311.0.0.2c554c4doDmpKd, is tight and has no more slop. For the curious, I adjusted the slop by removing the top plate of the table, loosening the bolts that hold it all together, taking a clamp and pulling the two sides in closer and then tightening the bolts. The table has a good pressure when moving feeding the table now. My only concern is how long the table will remain solid.

Thanks to everyone in here for all the help!

Updated with completed photo and video.

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I meant to comment on your blade slipping on the chuck when grinding. There are two methods I use to prevent this. One is to use a thin bar perhaps 1/2" wide and thinner than the blade you're grinding. Put in a magnet slot so it will catch on the edge of the aluminum that rises above the magnet. Another simple method is to drill an 1/8" hole in aluminum chuck perhaps 3/16" deep. Stick an 1/8" brass rod just long enough to stick above the aluminum the thickness of the tang. You do have a hole drilled in tang? Put the brass rod thru the hole in tang and it will hold blade in place while grinding. Either method works pretty good.
 
I'm a total newb, but I can definitely see the usefulness of this just in the small number of knives I've made.

I'd like to try one myself, but I don't have access to a mill. Is the chuck the only piece that actually needs to be milled? Everything else more or less bolts on?
 
So I see that everyone mounts the slide rail so that it is in the same plane as the contact wheel or perpendicular to the wheel axle. This is obviously done to keep the blade directly in line with the belt.

If the slide rail was mounted at a slight angle maybe 85 degrees in stead of 90 but the chuck was mounted in the same plane as the wheel this would mean the blade would cross back and forth across the belt for more even ware. This would also allow 2" beltso to grind a wife blade.

It may help to improve finish also as the rolled edges of the belt would track across the blade maybe evening things out.

I want to make one of these and was considering this mod.
 
Ken H> said:
I meant to comment on your blade slipping on the chuck when grinding. There are two methods I use to prevent this. One is to use a thin bar perhaps 1/2" wide and thinner than the blade you're grinding. Put in a magnet slot so it will catch on the edge of the aluminum that rises above the magnet. Another simple method is to drill an 1/8" hole in aluminum chuck perhaps 3/16" deep. Stick an 1/8" brass rod just long enough to stick above the aluminum the thickness of the tang. You do have a hole drilled in tang? Put the brass rod thru the hole in tang and it will hold blade in place while grinding. Either method works pretty good.
Click to expand...

Those are great ideas to handle weak magnets. I would have to use the pin method to secure the blade from slipping. The magnets are level with the face of the chuck. I ordered N52 magnets, and will be remaking the chuck. This time I will set the magnets 1/8" deeper into the chuck. I am curious what size of magnets and strength the TW SGA uses.


BubbaW said:
I'm a total newb, but I can definitely see the usefulness of this just in the small number of knives I've made.

I'd like to try one myself, but I don't have access to a mill. Is the chuck the only piece that actually needs to be milled? Everything else more or less bolts on?
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The chuck is the only thing milled on my build. I had a local shop do it. The other parts of the build can be done easily. Measure, drill, tap, test.

Reeder just announced their SGA, and in their videos promoting it, they have mentioned that the chuck will be available for sale as its a wear item. https://reederproducts.com/shop?olsPage=products/rps500-surface-grinder-c0db55d6-ad2d-44ce-a61f-980d82d3c2b2. Keep an eye on their stuff and I am sure it will pop up.
 
bmilleker said:
hose are great ideas to handle weak magnets. I would have to use the pin method to secure the blade from slipping. The magnets are level with the face of the chuck. I ordered N52 magnets, and will be remaking the chuck. This time I will set the magnets 1/8" deeper into the chuck. I am curious what size of magnets and strength the TW SGA uses.
Click to expand...
I got the idea of the bar across the chuck from one of Travis's videos on his SGA. Even with N52 magnets there will be sometimes the blade will try to slip, especially with smaller blades and heavy grinds.
 
I have updated Post 473 with a completed video and photo. https://bladeforums.com/threads/home-built-surface-grinder.1532559/page-24#post-18794491

Regarding the magnets and holding, I used a 1/16" thick piece that spanned the width of the chuck to act as the fence. I had no slipping issues after that. In the video, I am surfacing aggressively with a 36g belt and had no issues.

The next thing to do is to make a non metal material holder. I am thinking two pieces of 3/32" steel with chisel grinds can use pressure to hold the material. The table feed will be tiny and the speed will be slow. I'll have to try this before I make something more complicated.
 
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