Bosch Recipricating Saw Question

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Forum topic by Shadowrider posted 06-06-2015 03:11 AM 876 views 0 times favorited 8 replies Add to Favorites Watch
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183 posts in 630 days

06-06-2015 03:11 AM

So I have some tree trimming to do and what better excuse to buy a new tool? I picked up a Bosch RS7 (11 amp) reciprocating saw at Lowes for $69.99 on sale.

I’m pretty impressed with it. I cut off a pretty large branch off of a 30year old cottonwood tree and am in the process of chopping it up. All of the small’ish parts are done. To illustrate the size that I have left I got 9” pruning blades and I’m going after some 12” in the morning because they won’t go through to the other side, though you can “roll” around the outside circumference and get through. It is probably around 10-11” at it’s biggest point. I really need a chain saw but one project just doesn’t justify one and for the rental cost I get a new tool.

Does anyone know what the duty cycle is or where to look it up? The saw is handling the cuts fine except for one thing. The gear drive is getting quite hot if I don’t stop and let it cool down. Almost too hot to hold with mechanics wear leather gloves. The motor is not balking one bit though, 11 amps is having no issue with the cuts and it has a good fan and is staying cool, I can’t imagine why one would need 13-15amps with this 11amp saw running like it does. I think the heat is transferring up the blade into the housing since it is essentially buried in the log and unable to dissipate much heat. Each cut is taking about 3 to 4 minutes going easy on the pressure. I apply a little pressure and rock the saw to keep the dust rolling out of the cut and not clogging up things. I’m doing a couple of cuts and giving it time to cool down. I guess my question is what is the duty cycle of these things and just how tough are they? They appear to be pretty dang good but I don’t want to push it too much.

Here is the saw:

8 replies so far

View dawsonbob's profile


1834 posts in 1176 days

#1 posted 06-06-2015 03:41 AM

I have that saw, although mine is old and looks like a train ran over it. Nevertheless, it keeps on churning, year after year.

Sometimes, though, a chainsaw really is the best thing. You might want to look at this one for probably less than a lot of places rent them.

Just a thought.

-- Mistakes are what pave the road to perfection

View MrUnix's profile (online now)


4030 posts in 1619 days

#2 posted 06-06-2015 04:03 AM

Have no idea about the duty cycle… but I would never use my reciprocating saw to trim trees. Green wood and sap is tough on a saw, and it will gunk it up pretty fast. Get a cheap chainsaw if you want to do landscaping!


-- Brad in FL - To be old and wise, you must first be young and stupid

View dhazelton's profile


2284 posts in 1717 days

#3 posted 06-06-2015 12:10 PM

10-11 inches thick is too much for a reciprocating saw. Get a chainsaw. And chaps. Electric chainsaws have more torque than gas ones so respect it. Keep the bar out of the dirt and you’ll be done in no time.

View Fred Hargis's profile

Fred Hargis

3844 posts in 1914 days

#4 posted 06-06-2015 12:38 PM

I don’t know if I’ve ever seen a “duty cycle” on a universal motor, though they are common on induction motors. I have that same saw, and a blade for tree trimming. It’s really handy, but I don’t use it in place of a chainsaw….only on smaller limbs/whatever. The problem your having isn’t the heat from the blade (IMHO) but the heat build up in the gearbox. In any case you have 2 choices: get the correct tool (chainsaw), or use your recip until it fails (if it fails) and see if warranty will repair it; technically the warranty is for defects, but who knows….you may luck out.

-- Our village hasn't lost it's idiot, he was elected to congress.

View alittleoff's profile


288 posts in 697 days

#5 posted 06-06-2015 01:33 PM

Your saw is probably continues duty cycle. Which means it will run continuously without overheating. That doesn’t mean you can cut logs with it all day though. It should cut what your doing without overheating if you take it easy and don’t force it. Your heat problem is probably caused by using an extension cord that is to small. Your cord should be at lest a no. 12 copper. 11 amps is a pretty good load when you hook it up with a 100 ft. Cord that’s to small or has loose connections. I don’t know what size your using, but I would check it and see, and use the shortest you can get away with.

View gfadvm's profile


14929 posts in 2110 days

#6 posted 06-07-2015 12:14 AM

I trim some small tree branches with my 18 V DeWalt and find the demolition blades work better than the thinner pruning blades (less pinching/binding and seem to clear green sawdust better). Anything bigger than 3” and I’m breaking out the chainsaw though.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View Tennessee's profile


2410 posts in 1935 days

#7 posted 06-07-2015 12:31 PM

What is happening is the tree sap is holding up the blade from going back and forth, putting undue strain on the reciprocating bearing and eccentric inside the housing.
There is not really a gear unit so to speak, but an eccentric bearing case on the motor shaft that causes a bearing inside of it, mounted on the sawblade shaft to go back and forth as the motor turns. (Actually, the bearing on the saw blade shaft is mounted at an angle so it goes back and forth.) At least this is what most of them are like.

I recently took a chance on an old Milwaukee at a yard sale for a dollar that turned out to have a broken bearing ring. It was more money to replace it than the work and saw was worth, so I ditched it.

I agree with most above, you don’t cut down tree limbs with a recip saw. You could blow the front end of the saw.

-- Paul, Tennessee,

View Ghidrah's profile


667 posts in 643 days

#8 posted 06-07-2015 04:59 PM

They make pruning blades for sawzalls, (recips) and they work fine, (super aggressive). I bought one in the early 90s just after hurricane bob hit the Cape and used it till the teeth got too small from filing in the early 00s. I cut pine, oak, cedar and maple with it. I bought my Stihl a week later, the recip wasn’t fast enough and neighbors were asking for help.

The 2 drawbacks to a recip are cord and slow.

-- I meant to do that!

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