Improving the Harbor Freight Chain Grinder

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KennyPete

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I was given a harbor freight chain grinder yesterday, so I figured I would tinker with it and see if I can improve on it a little before passing it on to someone else. Out of the box it's what you would expect from Harbor Freight. It works, just not very well. So here is my less than 2 dollar fix.

I identified a few problems:

1.) The bike handle clamp mechanism sucks. Even with the adjustments all the way out it didn't provide sufficient clamping. It did not hold a consistent height, and it liked to get hung up.

2.) The spacers between the rails were at .088, so there was a lot of play.

3.) The grinding wheel sucks.

4.) The pivot lever had a lot of play in it and didn't provide consistent cuts. The pin is .390 and the holes on the grinder were at .432 - tons of slop.​

Here is how I fixed them:

1.) To fix it hanging up, I disassembled the clamp and took a file to the rails and clamp piece and knocked off the sharp edges.

2.) To fix the space between the rails, I replaced them with some .060 washers, putting the old spacers (split ring lock washers) on the outside, and tightening it down.

3.) The chain advance mechanisms were .050 so I left them in place. If I were doing it again I would toss them and put washers in their place.

4.) The cable had a lot of slop where it goes in to the clamp, so I put 2 layers of adhesive heat shrink on it to tighten up the gap. Seems to be a good fit.

5.) I added a .125" thick washer to the clamp piece to tighten up the cable. It made a hell of an improvement.

6.) Finally, I addressed the big problem - the shaft play on the pivot lever. While the holes in the base were fairly tight, the ones on the ginder side were very sloppy. I milled two brass bushings - .390 ID .503 OD (3 thousandths oversize for a tight press fit). Then I took a 1/2" drill bit and bored out the holes on the grinder. The bushings took the majority of the slop out of the unit.

7.) OPTIONAL - I made a cheap stand for it out of some scrap lumber and a old tire rim I had laying around. I also put a piece of aluminum tape on the plastic depth control base, as it was getting hit with sparks. I'm going to pass it off with the crappy grinding disc it came with, but advise them to get a good one from Baileys.​



These fixes made a vast improvement in this cheap machine. While it is nowhere near as precise, adjustable, powerful, or durable as my EFCO grinders, it is roughly 1/16th the cost. If you're willing to put in a little work to make it function better, it's perfect for anyone who can't justify spending $350+ for a good grinder to their wife haha.

I hope this helps you guys out somehow. I have gained a lot of knowledge from here in the past couple months, bought and sold a few saws, made a few friends, and I would like to give back to the community.



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Nice work KP.
It's still a harbor freight special, but like you said, if the wife won't let you buy one for $350 lol. I have $350 into all 3 of mine, 2 efcos(one with the hydraulic clamp) and an oregon:). I use one for .325, one for .375, and one for the rakers.
Maybe someone could do the mods on these and sell them to make enough to buy a better quality one.
If there is a specific model # on the gringder it may help others looking to make improvements find this.
Great job again.
 
Very cool! I have looked at them a couple of times now and considered doing something very similar, especially concerning the main pivot shaft. This is right up my alley - making something serviceable out of an inexpensive tool by using my time and ability instead of paying someone else.
 
Sounds like a plan Chris.

If you don't have a lathe at your disposal, you could get some off the shelf 3/8 ID x 1/2 OD bushings, drill the base out too, and use a 3/8 pin. Tractor supply carries them, probably run you about $15 including the pin and E clips.
 
I think something that would benefit this model grinder is to move the brake lever off to the side (for the other hand) so that a lighter touch can be put on engaging the grinder wheel. I had one of these (passed it on) and an earlier HF model with a lever clamp that I still use. The "play" can be utilized by being able to engage a tooth that is a little short or long. Clamping the brake handle and swinging the grinder makes for too erratic of a grind as it's hard not to vary the engagement. I'm sure tightening the bushings helps with this but I think relocating the handle would be a worthwhile improvement. I have several other grinders so don't expect to go back to this model.
 
Damnit, you have a valid point and now you have me thinking. I might relocate the brake mechanism next week when I have some time. Perhaps adding a dowel rod on the left side of the grinder and mounting the brake handle to that. It certainly would help the feel of the unit and prevent ham-fisted operation.
 
I would relocate the handle to be a foot peddle. With that you have the second hand free to easily move the chain on.

7
That's a great idea sleeper, I was wanting to do that with my efco hydraulic. It works as you pull the head down. When you are adjusting how much you want to take off the tooth it makes it harder to adjust. A foot pedal gives you one hand to operate the head and another to move the chain forward to the next tooth.
 
The only disadvantage of moving it to a foot pedal is that would require parts and increase the cost of the unit. It also would be a more complex conversion than just moving the handle off the grinder head. It would work well though in my estimation.
 
The only disadvantage of moving it to a foot pedal is that would require parts and increase the cost of the unit. It also would be a more complex conversion than just moving the handle off the grinder head. It would work well though in my estimation.
In light of the above mods, it would be a "lite" conversion lol.
 
While relocating it to a foot pedal would be super convenient, I dont feel the added cost and and fabrication time is worth it for THIS grinder. If it was a efco, tecomec, Oregon, etc. - hell yeah do it to it!
 
Now you got me thinking.. Attach a piece of cable to the stock brake trigger.. Run it down the 4x4 to a sprung foot pedal that is welded to the tire rim. Boom, foot control. Disregard my last comment haha.
 
Come on guys be serious! How expensive is it to use a cable and sheath from a rear wheel brake of an old bycicle? Welding on a piece of the old bycicle handlebar for the grip and the grip can stay the same, simply transfered from hand to foot use. So even if you don't have a junk yard to pick the parts off brand new the cost for cable and shaeth would only be around 10-15$!

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