Belt sander grit for reprofile

[bladerique]

I'm thinking about renting a belt sander to reprofile some blades. What is a good grit for that? Also, what's a good width? I was just looking at the specs of a 3" wide belt sander -- too wide?

 

[tabeeb762]

I don't own a belt grinder, because they don't sell them in my area, but I'll give some advice anyway.

There is a learning curve on most sharpening methods. I've you've never used a grinder before don't expect to start laying down perfect edges on your first day.
You might even ruin a few knives in the process so be prepared to rent one for a week or more.

3" sounds like a woodworking sander. The type most often referenced here is the 1" x30". They run $40 or less at Harbor Freight. Sure the 3" is wider, but it will be harder to find grinding instead of sanding belts, and your grit range will be limited.

Knifemaker Jerry Hossom has a great tutorial on belt sanders and sharpening. I suggest you search for it and read up if you haven't already.

 

[Andrew Colglazier]

I'm thinking about renting a belt sander to reprofile some blades. What is a good grit for that? Also, what's a good width? I was just looking at the specs of a 3" wide belt sander -- too wide?

I don't know what you have available to you, but I use a Craftsman 1x42" sander. What to use for reprofiling kind of depends what thickness of steel you are working with. I find that a very rough grit is good for such work because it tends to generate less heat to damage the temper of the blade.

Andy

 

[Dag-nabit]

I don't know what you have available to you, but I use a Craftsman 1x42" sander. What to use for reprofiling kind of depends what thickness of steel you are working with. I find that a very rough grit is good for such work because it tends to generate less heat to damage the temper of the blade.

Andy

Agreed

I use a Kalamazoo 1x42 because it has a slower belt speed of 1800FPM.

I have used, and still do on occassion, the 1x30 harbour frieght type belt sander. These units run at, I believe, around 3300 FPM belt speed.

Either will do the job, but if you have options available, I would try to rent one with a slower belt speed. 1" belt width will work well for what you want to do.

As previously mentioned, any sharpening method takes practice. It is important to keep your work moiving on a belt sander, and to use the correct pressure (light pressure, let the belt do the work)

If you rent one, plan on having it for a few extra days to allow yourself time to practice on some old blades first.

Depending on blade thickness, abrasion resistance of the steel, etc, etc, etc, I have started with as low as 60 or 80 grit belts to establish the initial profile. Then I work my way up to approx. 1200 grit before stropping.

I increase in increments of approx. double the previous grit, i.e. 60, 120, 240, 600, 1200.

If you start with very coarse grit, it will take you some extra time as you work your up through the next couple belts to work out any of the deeper scratches. (that is my experience at least) but with practice you can achieve an excellent polished edge as the end result.

Kevin

PS Also suggested previously, there is a wealth of informational videos available on line on how to reprofile/sharpen with a belt sander. If you haven't already done so, Google up a few and watch them before starting.

 

[pwet]

take care with 60grit belt. that's what is used to grind a blade. i wouldn't suggest starting that rough for a begginer. you can make a kriss out of a proper knife in no time with a 60 belt.

 

[Incahiker]

I use 80 grit to reprofile, only takes about 1 to to swipes on each side.. but... you must be very confident in your abilities because it only takes on small mistake to completely ruin the bevels of your blades or make them look like crap.. But to me it is better to get it right the first time rather then having to take a dozen passes on the belt. You increase the chance of mistake with every pass. Then I move onto 200, 400, etc.. until it is mirror polished.

I start on a worn out 400 grit for a knife that just needs to be sharpened, not reprofiled. Works very well then I jump to 900 grit then polish. Just takes a second.

 

[michaelm466]

I use a 1x30 belt grinder, the narrower belt will be easier to follow any curves on your blade especially with recurves it will be easier with a narrower belt. I find a 600 grit belt to work well for reprofiling with 2-3 passes on each side for every every steel except ZDP-189 so far including S30V and M4. I then go to 800, 1000 and then mirror polish with a leather belt with compound.

 

[bladerique]

Just so you guys know, I have some minor projects to work on, but this is the main one:

Coming in Wednesday, with a lousy factory edge.

Oh yeah, I'd like to heat and flatten some PVC for a sheath insert, as has been done many times by bladeforum members, but what size PVC?