Bosch GCM 12SD saw not flat

[Robin Frierson]

So upgraded my miter saw to the Bosch 12in glide and it arrived few days ago. Upon inspection found the left side of the table .012 out of flat. I had read others had experienced this problem but thought the issue was corrected. Ordered through Amazon so guess I will send it back. I like pretty much everything on the saw except the safety latch to turn on the saw. Anyone else suffer this issue?

[John TenEyck]

Another bummer, Robin. You must be on the list where companies send their less than perfect equipment.

Send it back.

John

[Art Mann]

I have to wonder how many people buy this saw or similar models and brands with the same problem and happily use them for decades without any knowledge or complaints. Being an engineer, I had to check my GCM 12SD for flatness with a precision straight edge. I found a similar situation but instead of returning the saw, I just started using it every day. I haven't yet found a situation where my observation made any difference. If you will do a little trigonometry on the amount of error you will get from this problem, you may find that it is in the few thousandths of an inch over many inches. There are many other error factors with the average SCMS that dwarf this one.

[Robin Frierson]

You have a good point there Art. I have owned two Dewalts before this new Bosch and never checked them for flat. But having read about the issue I had to check and since its a simple return I think I would prefer one that is flatter, even though the difference may not be reflected much in the end product. Also in reading some previous threads someone posted the tolerances for Bosch is .019.....so my saw is within Bosch tolerances.

"You must be on the list where companies send their less than perfect equipment."

You could be right there John...at least this will not be as hard as returning a jointer, or replacing the motor in the second jointer.

[Osvaldo Cristo]

I have to wonder how many people buy this saw or similar models and brands with the same problem and happily use them for decades without any knowledge or complaints. Being an engineer, I had to check my GCM 12SD for flatness with a precision straight edge. I found a similar situation but instead of returning the saw, I just started using it every day. I haven't yet found a situation where my observation made any difference. If you will do a little trigonometry on the amount of error you will get from this problem, you may find that it is in the few thousandths of an inch over many inches. There are many other error factors with the average SCMS that dwarf this one.

Another Engineer here... :-)

I was to write exactly the same as you as I have similar experience... I fully agree you.

All the best.

[Ben Rivel]

Yet another engineer here, and I guess I must have lucked out, because IMO my brand new Bosch GCM12SD that I bought for $450 shipped from AcmeTools.com using their holiday one tool purchase 20% off coupon came pretty darn flat. Slapped the Starrett 24" straight edge on it and over the whole 24" its plenty flat enough. I was able to find one high spot on the left side of the rotating table and it was 12 thou out. But the over the length of the entire table this wasnt an issue (ie no rocking of the straight edge side to side).

Also the table to fence was extremely square as well.

Got a Forrest ChopMaster on their and the blade to table squareness at the 0 degree stops was perfect as well. The 0 degree miter detent needed a hair adjustment, but that was really easy to fix. Powered it on though haven't even had a chance to make a cut with it, but so far everything looks good.

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[John TenEyck]

Yet another engineer here not that it makes a differnce. On my Bosch DCMS (non slider) the center table is lower than the outer frame by enough that a work piece rocks on it. The ZCI is lower still. I would have returned the saw but I needed it right then (Lesson to never buy a tool when you need it.) so I put a piece of plywood over the whole thing and it worked fine. W/O the plywood parts would tip down and weren't square after cutting. It was painfully obvious when you put two parts together. In order to eliminate the plywood I eventually made a new ZCI that is proud of the center table and flush with the outer frame.

BTW, not one adjustment was correct on that saw. It didn't cut square vertically or to the fence, the 45° stops were off, same for the bevels. I spent a very unhappy 2 hours getting it dialed in. Fortunately, it has stayed in pretty good adjustment for the 6 or 7 years I've owned it.

I expected better from Bosch.

John

[Jerry Wright]

Using a little trig and a .012" bump 10 inches from the blade introduces an error In the 90 degree cut of about .06 degrees. May be hard to see that with a machinist's square on a 1 inch thick board. Just sayin'. What am I missing??

[Robert Hayward]

I like pretty much everything on the saw except the safety latch to turn on the saw.

That safety latch or button made my saw almost impossible for me to use with my right hand. The thumb on my right hand does not have a knuckle, a straight rigid thumb. I could not press the button and turn on the saw with one hand, using my right hand that is. Plus I found it annoying having to press the button even with my good left hand. Not that I would suggest defeating a safety feature, but that button is very easy to defeat. I forget now, but six or eight screws and the entire mechanism is exposed. Maybe five minutes if you count getting out and putting away the phillips driver. Note that the drive belt cover must be removed also.

[Nathan Ginder]

I've had 2 of these Bosch GCM12SD saws. Both had table flatness issues, and miter detent / fence alignment issues. After squaring the saw(s) at zero degree, then checking for square on opposite side of blade it was always off (or not close enough for me)... Tried a never ending game of using paper shims to align fences, but you just can't totally fix poor milling/casting. The 45 degree detents (both left & right) were horribly wrong too, more like 46.5 degrees.

I'm sure everyone out there with the Bosch glider would have checked/noticed 45 degree accuracy but if not, maybe look into it. Bosch service said they haven't heard of this issue, I returned first saw and second saw was the same. I really wanted to like the Bosch but these issues were to much for me. I now have a Makita 12" non slider which has none of the issues the Bosch had.

[Osvaldo Cristo]

Using a little trig and a .012" bump 10 inches from the blade introduces an error In the 90 degree cut of about .06 degrees. May be hard to see that with a machinist's square on a 1 inch thick board. Just sayin'. What am I missing??

You are missing nothing... Although I did not check your calculations I think it is right or very close... It can be a huge error for some applications but not for ordinary woodworking.

There is no a such thing as "dead on" measure... always there will be an error... the point is where it is good enough.

[John TenEyck]

Using a little trig and a .012" bump 10 inches from the blade introduces an error In the 90 degree cut of about .06 degrees. May be hard to see that with a machinist's square on a 1 inch thick board. Just sayin'. What am I missing??

Assuming your saw cuts a perfect 90 deg vertically, go put a few sheets of paper equal to 0.012" under one end of your 10" long piece (and it's actually not that long from my blade slot to the outer frame) and cut it off. Do the same on another piece. Lay the parts on a flat surface with the cut ends facing each other. See a gap?

When I have to use a shooting board to square the end of a cut, vertically, the saw doesn't meet my needs. Your needs may be different.

John

[Jerry Wright]

You are right. The gap would be 1/256". My best wood doesn't stay that good.