Fixing cut off saw

[czechsonofagun]

My cut off saw stopped working some time ago. It is the cheapest HF model:

Harbor Freight Tools - Quality Tools at the Lowest Prices

On Sunday I decided to take it apart before I take it to scrap and that thing is actually fixable.
On the end of the motor are brushes, they go in from outside in some kind of a socket. The field connects to that socket on the inside with a spring loop and this spring loop burned out on one side. I tried to replace the spring loop with a wire and it actually worked before the wire burned out. I have two questions:

1. What would be the name of that spring loop? 2. Is there a place to buy it from? It looks like it is a part of the field - and I dont want to buy whole new field, but it must exist somewhere. Seems to be brass spring (it is harder than copper).

And yes, the saw is like $60 at HF - and this one I built two trailers with and tire carrier and landscaping rake and many other things; it definitely paid for itself but to fix it is a challenge, I am sure you understand.

 

[Podunkadunk]

I pulled up your saw on Chicago Electric's website. Then downloaded the manual for it. In the manual it lists the below number for questions and parts...

Then I called the number, it was Harbor Freight's customer service number. Don't know why they did it that way, especially since it was on Chicago Electric's website and their manual...doesn't really matter...

Anyhow, I'm sure they can point you in the right direction.

1-800-444-3353.

 

[czechsonofagun]

I pulled up your saw on Chicago Electric's website. Then downloaded the manual for it. In the manual it lists the below number for questions and parts...

Then I called the number, it was Harbor Freight's customer service number. Don't know why they did it that way, especially since it was on Chicago Electric's website and their manual...doesn't really matter...

Anyhow, I'm sure they can point you in the right direction.

1-800-444-3353.

Thank you, sir

 

[Redbug]

Hi Czech,

I bought one of those saws, also. Guess what? That's exactly what happened to mine! And I did not get much use out of it when it happened. I took it apart and soldiered the spring loop back together and also added a small piece of wire into the loop section. That thing would work intermittantly and spark like crazy until I did my solder job.

After that, I was always a little paranoid about using the saw. My confidence in it had worn thin. Electrocution maybe?

It had also developed a little slop in the hinge which made the cuts uneven. I finally trashed it and bought a better quality Dewalt D type handle chop saw that Patrick G suggested. More money...but it cuts much better and I have never been happier. I would say you definately got your $60 out of it from all the things you built with it...more use than I ever got with mine!

 

[nobull1]

• We always called them garter springs, but it isn't the correct name. The reason it broke is the problem though. Here are a couple of the most common reasons it may have burnt​

​

• Low voltage: to long or too small of an extension cord​
• burnt field: causing excessive amperage​
• open circuit armature: excessive heat​
• overloading of tool (excessive down pressure ) Most common problem with cut off saws​
• Any combination of the above​

In my years of fixing power tools a burnt garter spring "usually" meant more serious problems. The easy fix we used to do was take a old spring off of another good field. We would cut the lead wire back about a 1.5" from the spring and then solder it to the field wire. It is easier than assembling the spring, clamp and retainer onto the old field. This is assuming you happen to have a old similar size garter. If you do install a garter spring take a amp meter and check the amperage, it should fluctuate very little, if it does fluctuate a lot you have other problems.

If you take a couple of close up pictures of the field and the commutator of the armature (part where the brushes ride) I can give you an educated guess as to the condition of the parts.​

 

[czechsonofagun]

Nobull, thanks for the post and the knowledge.

I believe overloading was the reason for the burn out. I checked the field with a meter for resistance and resistance against the ground and both half are the same - that makes me believe the field is ok.

Yes, I was planning to solder new garter spring instead of the broken one, the problem is finding one. My last idea was to use a spring from an old oil seal.

My high school was specialized in electro engineering and we actually did some field rewinding and rebuilding, but I am not going to try it at home, it is not worth it in this case. Also the commutator could use some smoothing on a lathe - which I dont have so it will have to stay the way it is.

 

[czechsonofagun]

It had also developed a little slop in the hinge which made the cuts uneven. I finally trashed it and bought a better quality Dewalt D type handle chop saw that Patrick G suggested. More money...but it cuts much better and I have never been happier. I would say you definately got your $60 out of it from all the things you built with it...more use than I ever got with mine!

Redbug - I hear you. If i had a big project coming - like the trailer I built for myself - I would definitely look into some brand saw, but for now I can not justify the expense, there are tools I need more than the saw.

 

[nobull1]

Don't use a spring from an oil seal. If it isn't as heavy as the one that you are replacing, it will burn off in short time. If the reason it burnt in the first place was overloading, there is a good chance it caused more damage than just the spring. The reason I wanted to see the armature was to look to see if it was open circuited. Sometimes excessive load will cause the crimped wires at the commutator to come loose and make a open circuit at that bar and the one 180 degrees away from it. The way to tell is to look for a excessive gap between two or more bars, that are not present at other bars. What happens is when the brushes hit that bar, that is open circuited, the brushes will spark at that point, which will cause a slight amperage fluctuation( the more open circuits the more fluctuation). The fields in my experience don't always show faults with just a ohm meter. Sometimes a trained eye will pick up problems that are pending. One thing to look for is discolouration of the covering on the copper wire. Another thing to look for is melting of the insulation usually found around where the garter spring is attached to the field. Any of the above field problems might show fine on a meter but are sure to cause you grief in the near future.
I have sold people an armature, after they told me the field was fine, and had them come back a day later saying the armature was defective. I then get them to bring in the field and find they need a new field and another new armature . You can imagine how those conversations go, especially when I would have checked and replaced the needed parts for $30.00 labour in the first place.

Anyhow I am telling you a lot more than you want to know I'm sure. If it was me I would go to one of your local repair shops and just get a used garter spring of original size or heavier from a old field, with a couple of inches of insulated wire still attached, then solder it on and use it tell it fails. Maybe there are no other problems, and that will be years from now.

Brian