Circular Saw Died - Was it me (n00b)?

[Hoopy Frood]

I am new to building and to this forum. I had a circular saw die on me today and I could really use some help figuring out what went wrong!

It was a SkilSaw 7 1/4", plug-in, 2.25 HP model 5150. I'm not sure of the vintage, it was older, perhaps late 80s or early 90s?

I had bought it used about two months ago and used it on and off again with no issues. I had only used it to cut soft lumber (2x4, 2x6) and thin sheets (1/4"-3/8" plywood and OSB). I'd used the same coarse-tooth carbide blade on it for all those jobs and, while that blade made rough edges on the sheets, I'm just practicing and learning and didn't really care.

Today I stared my first big project using 3/4" OSB. Since this is supposed to be nicely finished I thought I would use a fine toothed plywood blade. I had inherited an old 140T blade in my shop and it didn't look too bad, so I put that on and started a 48" cross cut on the sheet. After 5 inches of struggling more than it should I stopped and decided to go buy a new blade. The new 140T blade (like the old one) was plain steel (not carbide). I figured that wouldn't matter for this project.

I put the new blade on the saw and started again. It was much slower than using a coarse-toothed blade, which I would expect. But it was smooth in the cut so I kept going. About 2/3 through the cross cut the motor started to bog down. I was only trimming 12" off the end of the sheet, but I moved my hip under the waste edge to support it so it wouldn't pinch the blade. The motor continued to bog and at one point the blade stopped in the arbor while the motor was still running.

I immediately released the trigger and pulled the saw back into the clear kerf. I let it sit for a few seconds. I didn't see or smell smoke and the blade and saw didn't seem unusually hot. After a bit I started the saw again and once it was running at speed moved it slowly back into the cut while being careful to support the waste strip. The blade stalled again and I released and backed off.

Once the blade came to rest I removed it from the cut entirely and tried pulling the trigger. Holding it in the motor started and stopped itself twice then just went silent.

I tested the outlet, it was good. I tried the saw in other working outlets to no avail. It wasn't overly hot and I didn't smell anything, but I let it cool in case it was a thermal cutout. Nope. With nothing working I decided to open it up.

What I found was not good. The brush contacts had both been pulled out of their housings, their springs wrapped around the axle and there were three adjacent commutator contacts that had broken off as well.

Now whether the commutator contacts broke off and tore out the brushes, or the brushes snagged and jammed into the commutator while it was spinning, I have no idea. Regardless this was a hard fail and I doubt it's worth trying to repair.

But how in the world did this happen? Was it just dumb luck? Or as an operator was I doing something wrong?

I never try to force a saw through material. I try to make sure all work and waste is adequately supported. There was about 1/4" of clearance of the saw teeth below the material. The saw had a warning sticker not to over tighten the arbor. But the arbor bolt basically bottoms out tightening with fingers, so I just made sure it was snug, not too tight.

I didn't see, smell, hear or feel anything grossly wrong as the failure occurred apart from the struggling motor and the blade stopping in the cut. Granted all the bits that broke are terribly small and flimsy compared to everything else...

I bought the vintage SkilSaw thinking the new stuff just doesn't last like the older stuff. Regardless now I have to buy a new saw before I can even start my project.

But if I screwed up and did something to break it I want to know so I don't break any more!

If anyone can help a noob out, it is much appreciated!

 

[pstemari]

You bought this used? I'm guessing the brushes were nearly gone, and when they bottomed out everything went to hell. The springs hit the commutator, snagged, and ripped it apart.

Take-away lesson is to inspect the brushes periodically.

Sent from my Nexus 6 using Tapatalk

 

[Richard Cranium]

You bought it used, It most likely was worn out before you got it. Go Buy a new one and have it for a very long time.

 

[lazer50]

Yeah the saw was more than likely at the end of its life.doesnt sound like you did anything wrong just buy you a good saw and take care of it.

 

[Hoopy Frood]

Holy cow. thanks for the fast replies! They're coming in faster than I can respond to them!

Duly noted, pstemari! I wasn't aware that they needed to be inspected and changed. Thanks for the tip!

Yes, I bought it used. For any folks that care to go down the post-mortem rabbit hole, one of the brush contacts survived the incident. The other is MIA (probably came loose and got ground up in the rotor).

Assuming the two were in similar shape before the failure, does this seem like a healthy amount of brush contact? (see the attached pic)



It looks maybe 50% worn to me, but what do I know

And, Richard C, I'm a homesteader and operate on a VERY limited budget. I wish I could afford reputable new saw. Any new tool I can afford likely has a reputation of dying VERY quickly (like first-use Harbor Freight horror stories). We have an excellent used tool source near us, but they only back products for a week. Yet I'm only out $16 on this one. I'm hoping they'll have another (they usually have 30-40 at any given time) that is in good shape. I'm learning more all the time as to what to look for.

And I'm all about taking care of things, lazer50! Preventive maintenance is a lot simpler than dealing with catastrophic failures!

Thank you, all!

 

[woody 73]

A parts breakdown for you:

http://www.ereplacementparts.com/skil-5150-type-f012515000-714-circular-saw-parts-c-130_160_831.html

 

[Hoopy Frood]

Superb!

I'm very happy I've stumbled unto this forum. I'd need to replace the armature since the commutator is toast - and if any crud got into the main body, maybe the field assembly would need to be replaced, too.

But every piece of knowledge helps. Thank you, all!!

I'm all about learning about how tools work and how to properly care for them. It feel like this is THE community to be a part of!

 

[bczygan]

Your next thread:

"What replacement circular saw should I buy?"


My answer is Makita.

Bill

 

[CNGsaves]

Next used saw to get . . . . . . worm-drive Skilsaw.

You won't be burning that one up !!

 

[wildbill23c]

Next used saw to get . . . . . . worm-drive Skilsaw.

You won't be burning that one up !!

If you do burn it up you really were working that saw hard, or you were running it on a cheap generator that caused the motor to burn up.

 

[Hoopy Frood]

Oh wow! The question of what brand has always been a pain because in any given year different brands crank out great stuff, but it seems there's no universal "great". Case and point how has Craftsman quality gone downhill over the bast 30 years? Or DeWalt in the past 10-15? I've used some excellent Makita tools and some not-very good ones.

Haha! The worm drive is not lost on me. At first I was thinking I didn't need a weight-lifting routine built into the build session, but I guess you can't argue with results!

Actually I found a couple Craftsman saws that I think were from the 60s at our local used tool place. They look to be built from, and able to do battle with, tanks! I swear one weighed like 30 lbs! But it probably won't burn out either :-D

 

[KenC]

You don't have to get new. I actually prefer used pro level tools to new if at the same price.

but, your choice of blades was incorrect for 3/4" OSB. 140 tooth blades take a lot of power to run in that dense stuff. and most of that style blades have little tooth set, so bind easily in long cuts. A good 24 or so tooth carbide utility blade is on my hand held saws most of the time.

 

[Hoopy Frood]

...your choice of blades was incorrect for 3/4" OSB. 140 tooth blades take a lot of power to run in that dense stuff. and most of that style blades have little tooth set, so bind easily in long cuts. A good 24 or so tooth carbide utility blade is on my hand held saws most of the time.

Ah, thank you! I was not familiar with the ins and outs of saw set. Yes, my 140T has very little set. Reading more on that now...

The saw came with a coarse-tooth, carbide tipped blade. It's locked in the shed so I can't count the teeth right now, but I will. It might be 24. It worked very well on everything I've done so far, it just had a little bit of splintering tear-out on the bottom side of the thin sheet materials. I've heard you can tape the bottom of a cut to minimize that?

So keep the 140T for fine work on thin (possibly laminates)?

I'm off to the used tool place to see what I can find! Of course now it's supposed to rain for two days so we'll see when I can actually test it out.

 

[Elginz]

Adjust the blade depth to the material, less splintering and binding, as well as the rest said.

 

[sberry]

I'm off to the used tool place to see what I can find! Of course now it's supposed to rain for two days so we'll see when I can actually test it out.

What,,,, didn't learn the first time and want to try it again? Buy a new brand saw, the old one is busticated. A new journeyman saw will outlast a homebody, doesn't even need to be the best or worm drive and as you learned,,, 150 spent on a new one and you would still be driving it, why go down used road again? While used is ok for some, I rarely buy it and only if it was so cheap that there was no loss if it dies tomorrow. Last thing I care to do is fix a saw or a grinder, same for impacts and air ratchets.
Sure it can be remanned, now a guy has 100 in parts in a used saw he could have got for 150 NIB. and it still doesn't work. or is about 50/50 if he is lucky at this type of thing, then you get to toss another 20 at it for a new cord too.

 

[Hoopy Frood]

Didn't learn? On the contrary I've learned quite a lot! And this forum has been instrumental.

One has to prioritize based on available resources. Most gainfully employed folks have ample money, but not a lot of free time. Buying new would make lots of sense in that case. But I'm a homesteader, so I have very little money, yet ample free time (that is by design - it's WHY I took up homesteading). I got a decent saw for about $15. It lasted two months, might have gone more if I had been wiser. It didn't, but I'm always learning...

I can buy 10 used saws for the price of one good new one. What are the chances that EVERY one of those 10 used saws fails like the first one I had? Vanishingly small I'd say. But even if they did fail it would be another nine saws and 18 months until I could officially kick myself and say "I should have bought the new one back then." Chances are I'll only go through one or two more before I find a great used one.

When every dollar counts, I play the odds. It's the course that makes the most sense given my life circumstances. People in differing circumstances will necessarily make different choices. There's no right or wrong in it, it's all about decently managing the resources you have available to you.

The store had surprisingly sold out of most of their stock! I've never seen that before. They usually have 30-40 saws there. There were only 10 or so today. There was a beautiful '50s vintage Craftsman for only $12, but it was a 6 1/2" so I didn't get it (I much prefer the 7 1/4").

Even though none of them were a good buy today, the stock usually changes weekly. I'm borrowing a saw tonight to finish my project. But I'm sure a great used buy will eventually come along as long as I'm patient and vigilant.

 

[finn]

I second getting a new saw. I bought a used Makita sliding miter saw a couple of years ago.

The field wiring burned out after a couple years of light use.

Parts add up to half the cost of a new saw, so, considering what I paid in the beginning, I would have been better off buying new.

No more used power tools for me.

 

[Hoopy Frood]

Nothing wrong with what you are doing OP, I play the used tool odds game all the time myself. Even with a few failures and/or duds thrown in I am still way ahead in terms of quality and price for my tools. You might want to ask the owner of the shop to give you a call if a good brand comes in so you have a chance to get it before anyone else swoops it up.

As I mentioned before, I don't think anything you did caused the failure of the first saw, but in general most consumer grade saws can't be pushed too hard reliably over the long term without having issues. In the future, try to always set your cutting speed with the primary goal of maintaining saw blade rpm. The saw ideally should drop rpm very little when it goes into the wood. If you can do that it will keep the saw at a low stress level at all times. If the blade is slowing down noticeably the cut is stressing the saw. If you end up needing to go really slow in order to maintain blade rpm you will often find the edges of the cut turning black from friction burn on the sides of the cut. That indicates either a dull blade, very dense or sap filled lumber, trying to cut through too much at once, or too weak of a saw for the job being asked of it. If that situation happens and you are short on options, try reducing the blade cutting depth and then perform your cut in two or more passes instead of just one. That can usually get you by in a pinch while also ensuring low stress on the saw.

Brilliant summary. When you put it that way it makes it very simple! I'll pay much closer attention to that as I work on this new project.

The shop gets the new tools each Saturday. They are a very friendly and helpful bunch, but they are pretty rigid on the first-come-first-served principle. I just have to make sure I'm there at the right time on any given week and I'll get to see what the tool fairy brought!

 

[Hoopy Frood]

I second getting a new saw. I bought a used Makita sliding miter saw a couple of years ago.

The field wiring burned out after a couple years of light use.

Parts add up to half the cost of a new saw, so, considering what I paid in the beginning, I would have been better off buying new.

No more used power tools for me.

I get that, but with a little luck an entirely different used saw can be got for a fraction of the cost of repairing an old one. I'm certainly not planning on fixing any used tool I spent $15 on if it costs more than $15 to do so! I'll spend the $15 on another potentially viable used tool and just get rid of the old one.

How does one get rid of an old, broken tool? We have an amazing recycling center that can take the scrap as one option. We also have a vibrant community of DIYers that will happily take the tool "carcass" if they see a use for it. For me, one way or another, the old, broken tool will benefit someone in the community. And I'm only out another $15 (or whatever) for the replacement.

But that's what works for me in my community. Again if someone has the money to buy new, go for it! Somebody's got to make the initial purchase in the endless stream of used equipment that flows through our store!

 

[sberry]

I didn't read very well and did not see you only paid scrap price for it. Different matter.

 

[jd_1138]

Where do you live? I have a Ryobi circular saw you can have for free. I just upgraded to a near mint Sears Craftsman "Sawmill" circular saw that I bought at a yard sale for $10. Used circular saws are pretty cheap.

But assuming you don't live in NE Ohio, if you do have the money, best to get a Skilsaw Magnum, Makita, DeWalt. I guess Skil names its good saws "Skilsaw" and just puts "Skil" on the el cheapo consumer models.

Also, the laser feature is pretty cool that some of these saws have -- makes cutting material easier. Though, my Ryobi and CM saws don't have the laser feature.

 

[Hoopy Frood]

Where do you live? I have a Ryobi circular saw you can have for free. I just upgraded to a near mint Sears Craftsman "Sawmill" circular saw that I bought at a yard sale for $10. Used circular saws are pretty cheap.

Maine, my friend Thanks for the info, though! I keep my eyes peeled on the local used place, Craigslist and the local "classifieds" which take a few different forms. Every bit of info on "what to look for" helps. Something will turn up soon!

In the mean time I've got the in-law's borrowed Craftsman 7 1/4". Probably circa '05. It's got the laser sight and even though I've used this saw a fair bit I could never figure out how to make the laser work. When I first borrowed it I had already gotten into the habit of constructing impromptu fences for every cut. Irwin Quick Clamps make it super easy! So I never used the laser and never felt the urge to.

I'm sure there must be raging debates among tool heads about which is better: the best freehand skill or great skill at temporary fences. Perhaps akin to the dreaded "What motor oil would you recommend?" threads on automotive forums

 

[SchwansManDan]

Most of the saws I have purchased over the years have been new, and they have lasted 20 or 30 years ... even the B&D circular saw that I bought back in the mid-80s is still working well.

The only saw I have bought used was a garage sale find ... $50 for a 10" miter saw that the little old lady swore was used by her late husband for only two projects before he died. I was inclined to believe her, and the damn thing still works.

 

[zendriver]

Seems like over the years, I have used skilsaws that were not all that.

It's fantasy to assume that everything old is always better that everything new, anyway IMO

A skilsaw setting unused on grandpas unheated garage shelf - for 25 years, might develop its own issues.

I have seen power tools at estate auctions that had rain water running out of them, from the leaking barn they have sat in for decades

I have a Skil saw that I've had about 20 years purchase new. It's not the greatest one in the world, but it still seems to get the job done. It was probably last of the American-made but it still feels cheesy compared to the higher-priced Mikita's and so forth



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[PT Doc]

Waste no more time on the circ saw. Got to HD and get a Milwaukee and forget about buying a new saw forever. Use good blades too.

 

[jd_1138]

Waste no more time on the circ saw. Got to HD and get a Milwaukee and forget about buying a new saw forever. Use good blades too.

Also, Makita, DeWalt, and Skilsaws are nice too. Really can't go wrong with any of the 4. And I would get a corded one. After getting a corded one, then maybe later pick up a cordless for convenience, but the corded is good for power.