Lawn Mower Blades

[Derek9D]

Im kind of getting tired of sharpening lawnmower blades with a handheld grinder so i thought about bringing them to school so i could cut the angle on the Vertical Miller but i need to know if they are hardened or not because if they are hardened i will not be able to cut them with an end-mill...So if anyone could please help me if you know wether blades are hardened or not.

[MOW PRO LAWN SERVICE]

No 90 percent are very soft.

[khouse]

if you have access to mills and such you should make a jig that mounts to your bench grinder for a precision angle and edge. regular blades are hardened - how much - I don't know. Do you have a rockwell or equal hardness tester? then you could compare aftermarket blades to oem. that would be good info.

[Raven386]

mow_pro.... i was just looking at your sig.... i think you might need some fluid film!

[Derek9D]

actually thanks thats a good idea to make a jig to mount on my bench grinder i just figured i could put them on a vice tilt the head to the req. angle and mill them. I'll try and check the hardness on the rockwell scale tommorow and see if they can be cut or not and ill try to figure something out to mount on the grinder....thankx for the info

[MOW PRO LAWN SERVICE]

LOL, good one got my free sample in the mail last week man that stuff is great sending a order out soon,after market or oem blades might be hard but to me they are very soft i sharpen blades daily makes the cut soo much better,as for jigs i went to the local machine shop and made a blade grinder works for me.

[Derek9D]

so whats this blade grinder jig look like if you have any pics because i think from a few pics i good make one in shop...I sharpened a set today on the Bridgeport using a carbide cutter and it works pretty good so i know the blades are somewhat soft since a file is around 60 rockwell and a file would take off material i didnt test them though all i need to do tommorow is make sure there balanced

[khouse]

just a triangular shaped tool rest that clamps to your grinder rest. then slide your blade back and forth on the angle rest while grinding.

[MOW PRO LAWN SERVICE]

What i meant was rest,you stated bridgport so you are in a machine shop i have a baldor 1 horse 10 inch grinder with a homemade rest to angle the pitch on a blade.

[Derek9D]

yeah thats what i thought where the flat tool rest is now i will just replace it by making a new tool rest at the blade angle i read somewhere its a 30 degree angle on the blade but i mesured it with a protracto on a new blade and i measered 35 degrees but i dont think 5 degrees will make much of a difference...thanx for all the help its greatly appreciated

[khouse]

the blade will hold it's edge longer at a higher degree. i think 35 deg. would be better. i always put a small micro edge on the back side maybe 1/64 inch wide. this will accually make the edge maybe 60 to 70 degrees right at the business end and it stays sharper longer. you can try it. it wears off in a couple of hours anyway.

[Derek9D]

thats true I've been told by this old guy who like knows everything that after the blade is sharpened if the tip or edge is rounded over a little it will last longer but for this kind of continuos cutting i dont think it matter since liek you said its going to wear out in a day anyway.

[gene gls]

actually thanks thats a good idea to make a jig to mount on my bench grinder i just figured i could put them on a vice tilt the head to the req. angle and mill them. I'll try and check the hardness on the rockwell scale tommorow and see if they can be cut or not and ill try to figure something out to mount on the grinder....thankx for the info

They can be milled, but its more trouble than its worth. The blades do not wear parrell. So you will be milling a lot off in areas that don't need it if you use the back edge against the stops on your milling table. I tried it, waste of time.

[Derek9D]

yes i encountered that today as you mill the closer to the center you get the more material comes off of the blade almost as if it was a tapered angle and yeah it is more work then its worth because it took quite a while to do probably would of been faster to grind them...Im going to just make a angle mount for the pedestal grinder

[Restrorob]

yes i encountered that today as you mill the closer to the center you get the more material comes off of the blade almost as if it was a tapered angle and yeah it is more work then its worth because it took quite a while to do probably would of been faster to grind them...Im going to just make a angle mount for the pedestal grinder

I kind of figured the dog was chasing his tail on this one.

One question; With a angle mount and a flat edge grinding stone what will you do when the blade is worn to a concave ?

IMO.... A little more practice with a angle grinder and you should be able to sharpen 3 without hot spots in 5 minutes as I do.

[Derek9D]

uh adjust the angle tool rest...A machinist must be able to make anything out of nothing in a small shop environment....ive read hat sime to many damn times in shop.

[lucforce]

Gotta go with rob here.

I sharpened blades on a bench grinder or with a six inch angle grinder for twelve years before I ever saw a blade grinding machine. I hated that machine. Had to constantly adjust the machine and dress the stones. Nush faster with a steady hand.

[Jay Ray]

You could use something like a 2" face mill with 4 carbide inserts and feed a lot faster than with a HSS endmill.

[Derek9D]

yeah i didnt use HSS mill i used a 3/4 4 flute centercut carbide endmill.....but the cutting is still slow....yeah ive been using just a regular portable hand grinder and it works alright with a little bit more practice i suppose i could do it but just wanted to try something different