Grinding small holes

JTknives

JTknives

Blade Heat Treating www.jarodtodd.com
Joined
Jun 11, 2006
Messages
8,647
So I am looking for a way to reduce the time it takes to clean up the finger holes on my Q3 blades. Normaly when I’m making one at a time it’s not a big deal. I have a crap ton of 1/4” sanding drums and just use thoes. But thy are cheep and it takes a handfull of them per hole. But now that I’m doing these knives in a large (120+) batch I don’t have time to waste changing out these tiny drums.

In my searching I found a few options I thought I would consider. First was just getting an oscillating spindle sander and use a 3/4” drum. But to make use of that long of a drum the stroke would have to be quite large. My other option is a sleeveless sanding drum that you can use sand paper with. This sounded perfect at first as I could use high quality paper or possibly a ceramic belt that’s cut into squares. Then I did some more searching and found this. 3M makes a Cubitron ceramic drum sleeve. The one I would be after is the 3/4”x1.5” 240grit and thy are like $17 for 10. There rubber drum sander is good up to 10,000 rpm.

But I’m not sure which way to go. I don’t think the spindle sander is the way to go anymore. Im thinking a simple drum sander chucked up in a high speed air tool. Then each blade is clamped in the vise and I zip around the ID with the drum. I don’t know what the RPM limit is on the sleeveless drum sanders and I’m worried I would not be able to hit the needed rpm with that set up if I went with chopped up ceremic belts. Would be a lot cheaper then buying drums but time is also money. Thanks guys for any help you can provide.

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I was thinking about that myself and thought if I were going to do 100 of these I'd make a little fixture and plunge cut the holes with a 1" endmill. Or I'd interpolate them at work but that doesn't help.
 
Hi JT, how about stones like these? I use them to clean up belt grinds on finger choils and other tight spots, can also handle minor shaping. Don't know about grit but they're not too coarse, kind of medium. Chuck them up in a hand drill I don't care about and it's pretty quick.

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mcmaster carr has .5 inch drums that in various sizes.
 
Make your own diamond bur .Try a few different grits or have one made.Its not very difficult. WB
 
From my knowledge diamond is a pore grinding median for steel. CDN works good though
 
What about something like a chucking reamer that's a few thou bigger than the hole? Should leave a pretty smooth finish. Then maybe a tumble in some fine ceramic to deburr and polish.
 
JTknives said:
So I am looking for a way to reduce the time it takes to clean up the finger holes on my Q3 blades. Normaly when I’m making one at a time it’s not a big deal. I have a crap ton of 1/4” sanding drums and just use thoes. But thy are cheep and it takes a handfull of them per hole. But now that I’m doing these knives in a large (120+) batch I don’t have time to waste changing out these tiny drums.

In my searching I found a few options I thought I would consider. First was just getting an oscillating spindle sander and use a 3/4” drum. But to make use of that long of a drum the stroke would have to be quite large. My other option is a sleeveless sanding drum that you can use sand paper with. This sounded perfect at first as I could use high quality paper or possibly a ceramic belt that’s cut into squares. Then I did some more searching and found this. 3M makes a Cubitron ceramic drum sleeve. The one I would be after is the 3/4”x1.5” 240grit and thy are like $17 for 10. There rubber drum sander is good up to 10,000 rpm.

But I’m not sure which way to go. I don’t think the spindle sander is the way to go anymore. Im thinking a simple drum sander chucked up in a high speed air tool. Then each blade is clamped in the vise and I zip around the ID with the drum. I don’t know what the RPM limit is on the sleeveless drum sanders and I’m worried I would not be able to hit the needed rpm with that set up if I went with chopped up ceremic belts. Would be a lot cheaper then buying drums but time is also money. Thanks guys for any help you can provide.


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You do that on annealed blade or hardened ?
 
Thy annealed, AEB-L and 15N20. The 15N20 is 42-43 RC.

I had thought about a carbide tipped reamer. I do have a big tumbler with ceremic media. That plan was to clean up all the edges and toss in the tumbler to smooth out the edges.
 
That , or if a little taper on both side is no problem ,maybe reamer for repair engine valve seats is best solution .............. ?
 
Might even try following a reamer with a wooden dowel and some valve lapping compound. You could probably lap 5 or 6 at a time without getting too crazy.
 
I have an oscillating drum sander and it works great for wood and metal work. Using a donut spacer block allows you to utilize more of the drum.
 
My first attempt will be just some ceremic belt wrapped around something and chucked in a drill. The hole allrrady has a nice finish from laser cutting so it just needs a little TLC.
 
I use a cheap home made router table and carbide burr... very fast, incredibly cheap and can leave a near mirror finish once you get good. It takes some time to get the right touch but I bet you will get it quickly. You can also cleanly chamfer the holes this way.
 
Daniel Fairly Knives said:
I use a cheap home made router table and carbide burr... very fast, incredibly cheap and can leave a near mirror finish once you get good. It takes some time to get the right touch but I bet you will get it quickly. You can also cleanly chamfer the holes this way.
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I am intrigued, have any pictures? What burr you using?
 
JTknives said:
I am intrigued, have any pictures? What burr you using?
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Check out post #6 for the Gavko video, he covers it better than I can. https://www.bladeforums.com/threads/router-w-flush-trim-bit.1584292/

I bought the cheapest router on the market from HF and it is awesome with plenty of power.

They are a bit tricky to use and kind of scary... safe but you do need to be careful and pay attention. Practice on a few pieces first. You need to feed the piece lightly and almost let the router control the speed as it feeds in and pulls if that makes any sense. I got the idea from Gavkos folder making video. I'm still not that happy with my burrs but you want a single flute (cut I mean... edit) 1/4" carbide burr, most likely ball/barrel shape.
 
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Wow that’s sweet, it’s going to be perfect. I’m surprised I have not heard of this befor. Just goes to show you how helpful everyone on here is. Thanks a ton
 
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