Questions regarding grinding slip joint blades

Signalprick

Signalprick

Jason Ritchie
Gold Member
Joined
Apr 3, 2009
Messages
3,260
Hey guys,
I finally got an opportunity to cut out, profile and practice grinding a 3" barlow blade last night. I had some scrap precision ground .105 O1 that I used, not heat treated. So my question here is what is the best grit to start with on these smaller type blades? I have 36 and 80 grit belts. Second, is practicing on soft steel a worthwhile way to practice? Or would getting the feel for hardened steel be a better way to go to start?
 
Put a handle on the blade.

I start at 50 grit and grind post heat treat.

I also like to start at the tip and grind my way back to the plunge, then work my way forward toward the tip.
 
AVigil said:
Put a handle on the blade.

I start at 50 grit and grind post heat treat.

I also like to start at the tip and grind my way back to the plunge, then work my way forward toward the tip.
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Adam, thank you for your reply! I actually just made myself a small handle out of a scrap piece of O1. Glad to know I'm one rhe right path there. I have gathered that grinding post HT is the way to go but for the sake of practice do you think I'm better off making a bunch of practice blades and just grinding them out or do you think I'd be better off going through the whole HT process and grinding that way?
 
Signalprick said:
Adam, thank you for your reply! I actually just made myself a small handle out of a scrap piece of O1. Glad to know I'm one rhe right path there. I have gathered that grinding post HT is the way to go but for the sake of practice do you think I'm better off making a bunch of practice blades and just grinding them out or do you think I'd be better off going through the whole HT process and grinding that way?
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If you are proficient at grinding just go for it.
If not I would get some tongue depressors, glue a couple together and practice on them.

Wood will show your faults much faster then steel.

That being said every single slipjoint maker will end up trashing a blade in the beginning.
The damn things are small and a mistake often is not salvageable like it is in a big fixed blade.

As you start making slipjoints just be aware shit can go sideways at anytime and you will have to start all over.
That is just a fact.
 
I start at 80 grit on heat treated blades, grinding before or after heat treat really doesn't matter but to me just saves a step. Gonna have to grind to final finish after heat treat anyway. Profile, set rise and fall, heat treat and grind.
 
Thank you guys! I bought a stick of cheap hot rolled steel from the hardware store today. Here's my 1st complete attempt. Did this one on the flat platen. 80 then 120 grit. No jig, although I do have one. I just can't get a feel for it. I also tried a pusher stick but I can't get a feel for that either. Guess I'm gonna have to live with warm booger fingers. 2nd practice blade in the works. Gonna try this one on my 12" wheel.

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There's 80 grit on the pile side with the wheel. Oddly I'm a righty but I'm a little more comfortable grinding the pile side than I am the mark side. I'm gonna do 4 or 5 more of these this weekend then cook up a couple O1 blades and see how it goes.
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I hollow grind all my blades on a 12" wheel, just be careful how deep you go with the 80 grit, or you will wind up way too thin after cleaning up the scratches. I do 80, 120, 400, 1200 then hand sand, edge thickness about .008.
 
SBuzek said:
these belts are a real game changer at 400 and 1200 grit
https://popsknife.supplies/collecti...ducts/deer-sa-331-2x72?variant=31051280547874
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Nice, I'm def. gonna need more belts! I'm struggling a little on that mark side. I think I get in a hurry or apply too much pressure? My right hand finger and thumb are fine but I can feel I burnt my thumb and finger on my left hand. I just need to get a better feel for it with my left hand I suppose. I was a little intimidated to try the wheel but I'm glad I did. I also think I need to lower my grinder down 2 or 3 inches. That will not be fun! :(
 
Don't grind to the spine with the low grit. Grind and leave a bit at the top and move it up with 120, and 220 grit.

Oh and drop down the speed. If you lower the speed as you clean up the blade you will make less mistakes.
 
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AVigil said:
Don't grind to the spine with the low grit. Grind and leave a bit at the top and move it up with 120, and 220 grit.

Oh and drop down the speed. If you lower the speed as you clean up the blade you will make less mistakes.
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Thanks for the tip. I will try that tomorrow. Neither of these blades did I run the VFD above 30. Do you take the edge right up to the "tracks" on the edge?
 
AVigil AVigil and SBuzek SBuzek I realize you guys are probably grinding freehand but as I practice this method myself I'm also using a 4" jig from DD Workrest in conjunction with my 12" wheel. My question is, what are good angles for doing my bevels? I've been using 12* roughly and it seems too steep. I end up reaching the spine way before I get near my center scribe line. Any help is appreciated. Thank you!
 
Signalprick said:
AVigil AVigil and SBuzek SBuzek I realize you guys are probably grinding freehand but as I practice this method myself I'm also using a 4" jig from DD Workrest in conjunction with my 12" wheel. My question is, what are good angles for doing my bevels? I've been using 12* roughly and it seems too steep. I end up reaching the spine way before I get near my center scribe line. Any help is appreciated. Thank you!
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Slipjoints follow pretty strict designs and many with specific grind lines people try to follow.

If youre making a blade thats 3/4" tall and the grind you want stops and creates a flat near the spine, the angle is whatever it is to connect those two points. I dont think doing the math is the right way to go.

If the grind goes above the spine, its about how much taper you want. Change your angle to "walk" your grind line in the direction you need, then connecting whatever to points you want, usually your scribed line on your edge and somewhere near the spine by the plunge. If you flat grind to the tip center, your taper is set automatically.

I hope that makes sense. Jigs, if you use them, seem more to me about holding a consistent, arbitrary angle to what your're trying to achieve with your grind line but I've always freehand ground so I dont have as much experience with them. Angles specific make sense in some sharpening activities .

Without a jig you do this a bit by feel where the belt is digging and also by watching the tiny sliver shadow between the belt and edge if it is there, at least thats the odd method I've developed over the years.

I dont use a stick. Burned fingers are punishment for grinding too hot and I accept that punishment :)

Lots of folder makers grind post HT but I've never really been able to do it and felt I was eating belts and worrying about heat a bit too much. I pregrind the swedges and almost finish them to final grit pre-HT. Everything else I leave thicker than I would a fixed blade but my main bevels are set, grind lines maybe 1/4" below where I want them to end. Nail nick goes in pre-HT as well.
 
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Grinding with a jig on a wheel?
I would set the edge of the blade at dead center of the wheel and then grind to the center line. Your wheel diameter will determine how high the grind will go.

Grinding free hand on a wheel really is pretty easy. Just establish a furrow and then apply pressure to move that furrow up toward the spine.

if in doubt slow down the machine, doing it slow will pay off with accuracy.
 
AVigil said:
Grinding with a jig on a wheel?
I would set the edge of the blade at dead center of the wheel and then grind to the center line. Your wheel diameter will determine how high the grind will go.

Grinding free hand on a wheel really is pretty easy. Just establish a furrow and then apply pressure to move that furrow up toward the spine.

if in doubt slow down the machine, doing it slow will pay off with accuracy.
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Thanks Adam. I'm running at 30 on my vfd. Is that still faster than you'd recommend?
 
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