Another Newby Error -Overheating During Grinding

tsavickas36

tsavickas36

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Alright dont bash me too hard as I am still learning everyday. I have had this happen multiple times in the last two months and I am sure I am doing something wrong but not sure how to overcome it.

I am new to this craft. I bought a bundle of 1/8" 1084 to start playing around. While grinding in my bevels I am repeatedly overheating and burning up tips etc when I get down to my finish bevel.

I have a Grizzly 2x42 and use new belts every time. I was using 36 grit but have gone to 80 or 120 to try and help. I did it again on my daughters knife this week. I dip the blade in water after every pass but it still seems to happen.

Am I using too thin of material at 1/8'? Should I use 3/16 or 1/4? Am I grinding too thin on my center line? If so how thick should I bring it before adjusting my angle to bring the bevel line up higher?

Maybe this is too loaded of a question but it is getting frustrating when I think I have a great knife in the making and burn things up.

Any guidance would be greatly appreciated.
 
I would say short quick passes with a low speed. Dip in water every pass like you're doing is good.
Make sure when you're grinding steel you have the grizzly speed on maybe 12-14. I have this exact grinder and that is the highest I will go for grinding steel.
Also, what kind of belts are you using? Get some ceramic ones if you don't have them already! I would definitely recommend red label abrasives ceramic 2x42 belts. I got a 6 pack of the 36 grit belts recently after having been using amazon ones for the longest time and they are MUCH better.
Hope this helps a little, Linus
 
Linus Knives said:
I would say short quick passes with a low speed. Dip in water every pass like you're doing is good.
Make sure when you're grinding steel you have the grizzly speed on maybe 12-14. I have this exact grinder and that is the highest I will go for grinding steel.
Also, what kind of belts are you using? Get some ceramic ones if you don't have them already! I would definitely recommend red label abrasives ceramic 2x42 belts. I got a 6 pack of the 36 grit belts recently after having been using amazon ones for the longest time and they are MUCH better.
Hope this helps a little, Linus
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Thank you I will try lower speeds. I originally bought a bunch from Grizzly but recently switched to Red Label Abraisives, they are only 15 min from my house.
 
If the knife has not been hardened yet, it does not matter that the tip got hot.

However, if you get it hot before HT you will likely get it hot after HT. That is the place where you can ruin the edge.

A 2X42 runs pretty fast, and most are not variable speed. That is teh issue. As belts get finer, they also make more friction. Dipping in water every pass and taking lighter passes helps, but variable speed is te answer in the long run.

One way to eliminate overheating is to set up a Kool-Mist type system and have the spray aimed 0right at the belt-blade spot. That will keep things cool even at high speed. The clones on Amazon work fine and are dirt cheap. I dev=finitely recommend the real Kool Mist lubricant #77 concentrate. It is a few bucks more a gallon, but seems better to some folks. A gallon will last a long time, since it is mixed 32:1.
 
1) slow the belt down
2) ceramic belts - hog the material with 36 or 60 then refine with higher
3) continuous movement. Don’t pause the knife on the belt in an effort to make grinding corrections.
4) dunk and swirl. A quick dunk sometimes isn’t enough if it’s going right back to the belt, especially as your steel thins.
5) like Stacy said, pre ht won’t ruin your blade. Post will.
6) good luck!
 
Quality belts ! Norton, 3M a German brand thats name I’m blanking on. Not Klingspor. Cheap belts are just that!
 
He mentioned he has a Grizzly 2X42, so I'd expect it's that variable speed grinder they released. If so, slow the belts down once the bevels get the edge below .040" or so. Ideally you'd look for a mister setup with footswitch to mist water on the edge while grinding. Not that expensive "IF" you've already got an air compressor. this is the $19 mister I'm using: B071DXGGP4 (in Amazon). This is the $17 footswitch: B08MF2F8GF (See Stacy, I didn't link anything and still gave an easy to find the item:)
 
Are you grinding freehand or using a bevel jig? If you’re using a jig get a good flat established and then switch to freehand grinding so you can feel the heat in the blade. When you dunk, feel the blade before you start grinding again to make sure it is at ambient temperature .

Slow the belt down and apply firm pressure. Make the belt cut instead of rub. Once you get a feel for it you might be able to bump the speed back up depending on belt type. Ceramic belts generally need higher speed and lots of pressure. AO belts need to run slower. No matter what type of belt you’re using, the finer the grit, the slower the belt needs to run. But remember, make the belt cut.

A mist system is a game changer when grinding. If you already have an air compressor that can run one you can be in business for $20-$30. If you don’t have an air compressor, buy one so you can run a mist system.

Experiment with different belts. I use 3M, Norton, VSM, Starcke, Deerfield, Klingspor, Hermes, Sankyo and a few others. I’ve got belts hanging everywhere in my shop. They all have their place.
 
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for me, being in a rush at the grinder often ends in disaster.

also, I've gotten into the habit of leaving a little lobe of extra material at the tip which helps a lot;
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GRapp said:
I've wondered about that myself and now will try it, thanks.

I usually dump some ice in my dip bucket, am I the only one?
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I have not done that- usually I'll just have a really full bucket so the water doesn't heat up too much.
 
I'll often dunk a paper towel in my bucket so it's soaked. Hold it against the back of the blade when pressing into the belt. The heat will transfer into the water of the paper towel. You still have to be light and careful and you loose dexterity but it may help
 
I leave the tip much blunter/longer and then trim it down once the final grinding is done, especially on warncliff/reverse tanto style knives.
 
I don't have a mister setup. I do the dunk method OFTEN. I try not to grind the bevel of the tip to much till the very last few grinds because it seems to grind thinner there way quicker. Oh and fresh new belts always helps.
 
scott kozub said:
I'll often dunk a paper towel in my bucket so it's soaked. Hold it against the back of the blade when pressing into the belt. The heat will transfer into the water of the paper towel. You still have to be light and careful and you loose dexterity but it may help
Click to expand...

I'm not a physics teacher, but I question IF this is a good idea?
If the cool wet rag is behind (away from) the edge.
Didn't all the friction and heat already work/be at the edge, first...already ruining the area.
 
Craig is correct.
The blade/grinder belt surface will heat to above 212° by friction. This will boil the water in the paper towel, and create a vapor layer between the wet paper and the hot blade. Vapor is not a good heat transfer medium compared to steel. That vapor area between the blade and the towel will stay at 212°F until all the water is gone from that junction. However, the transfer of the heat from the friction side to the steam side is not instantaneous, so the surface touching the belt, and even the other side, could easily rise above 400° and affect temper.

Caution to new makers who haven't learned physics the hard way:
Many of us wear knit or leather gloves when working in the forge and shop. They often wear them in grinding, too.
Water turns to steam instantaneously at 212°F (at 14.696PSI). Using wet gloves ... even very sweaty ones ... can give you first and second degree burns on your fingertips and hands as you touch the hot area of the blade in grinding. It is many times worse when grabbing hot tongs or a forged blade at black heat. If your gloves get wet, change them to dry gloves.
 
12345678910 said:
Hermes ?

Website Hermes Schleifmittel GmbH

Online presence of the Hamburg abrasive tool manufacturer Hermes Schleifmittel GmbH
www.hermes-schleifwerkzeuge.com www.hermes-schleifwerkzeuge.com
Click to expand...
Yes, Hermes Their Blue super flex handle shaping & finishing are excellent & VSM ceramic which are low cost efficient that working on heat treated steel blades I could use one new belt each per blade 60-120 etc & then they go in the profiling tear it up pile till dead!
 
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