# Sliding CMS--10" or 12"??



## greenacres2 (Dec 23, 2011)

Over the past few months I've been considering replacing my RAS (Craftsman, circa 1988 with recall kit, purchased used) and miter saw (craftsman, 10" bottom of barrel, purchased new in 1993) with a sliding CMS. The RAS is used almost exclusively for cross-cuts to right at 12" and the occasional dado, but I've been doing most of my dados on the table saw or with a router. The miter saw just isn't accurate enough for anything beyond rough framing if that--never really has been, but I now i'm aware of it.

I've built up a pretty good collection of 10" rip and cross-cut blades, so I was thinking that a 10" slider with 12" cross-cut would not lose any ground and i'd be able to interchange the 60 tooth blades between table and slider. Mitering would have to get better than what I've had, no way to get worse.

So...this week I've noticed that Dewalt has come out with a new 12" slider and I've seen their DW718 12" at prices below the DW717. Pretty decent saw, but it would blow that blade interchange theory out of the water. On the other hand--the 90 degree cross-cut can reach up to 16", with vertical moulding cuts up to 6" and some change. 

Anybody know if there's a replacement on the way for the DW717 10" that might bring it's price down some? I'm not in a hurry so if it's in the pipeline it might make some sense to wait. Thanks!!
earl


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## DaninVan (Jan 1, 2012)

Earl; if you're in the market for a new CMS, have you given the Bosch some consideration?
GCM12SD 12" Dual-Bevel Glide Miter Saw | Bosch


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## greenacres2 (Dec 23, 2011)

Oh i have. If money were not an issue--the GCM12SD would be a dream come true. All the capacity, about half the depth requirement, up-front controls. Seems like it's relatively light as well. It's that $700 price tag that gets a little hard to justify for a hack hobbyist!!

earl


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## MT Stringer (Aug 15, 2012)

I bought the Hitachi 12 inch slider a few weeks ago and simply love it. $399 at Lowe's.


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## MAFoElffen (Jun 8, 2012)

Earl,

As you know, I worked in the trades for years. I used to own a Makita 12" SCMS, then a Dewalt 12" SCMS... I wore those two out and then went to a 10" SCMS and never regretted it a bit.

On SCMS'es cutting compound miters I got less blade flex with a 10" compared to a 12" blade. Secondary was that a 10" SCMS was easier on my back lugging it around from jobsite to jobsite... and putting it away each night and setting it up in the morning. Then the blades were a lot cheaper... On the blades I was using for finishing, $40-80 compared to $70 to $125. I still have 10" and 12" blades I use on my TS, so they were not wasted.

PhilP had told me, he had switch to a 10" for the same reasons.

When I went back down to a 10" SCMS, I tried a lot different brands of saws. That's an advantage of working with other finish carpenters. Though I had planned for and could have spent a lot more money, as I considered that kind of saw as my bread and butter... That's how I made my money... Don't laugh. I didn't choose by price. My final choice surprised me. The one I picked, of all things, was a Ryobi 10" SCMS.

It had the most reach on the slide at the time I bought it (don't know about now), easy to read and get your angles, easy to zero and tune, keeps it's tune and it is very light in weight comparatively. 

I've had mine 7 years through heavy commercial use and I haven't worn this thing down yet at all. Surprising, as I wore out my Makita and Dewalt in about 4-5 years of the same heavy use. Heavy use? Every day, a lot on any day... most of the day during trim outs. SCMS'es were the tool I used most on any jobsite I was on.

I have replaced a couple parts (dust tube and cord wrap hook), but that was when someone knocked my kickstand over with a gluelamb beam, not from wearing out.

Has worked out well for me.


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## Big Steve (Feb 12, 2012)

I purchased the Makita 10 in. Dual Slide Compound Miter Saw, with Laser
Model # LS1016L about 15mos ago and love it. Will handle your 12" crosscut, about 4"+ on baseboard height.

Smooth cuts with provided blade.


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## Cherryville Chuck (Sep 28, 2010)

MAFoElffen said:


> Earl,
> 
> On SCMS'es cutting compound miters I got less blade flex with a 10" compared to a 12" blade.
> 
> PhilP had told me, he had switch to a 10" for the same reasons.


Someone posted a little while back, maybe it was BJ, that an 8 or 8 1/2' blade will do even better. I bought what I thought was a good miter blade for a Makita chop saw for $60. I found out that you have to spend a lot more than that for a really good one. I also found out that you can improve an average blades performance significantly by using blade stabilizers. Even Forrest recommends them for their blades.


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## MAFoElffen (Jun 8, 2012)

Cherryville Chuck said:


> Someone posted a little while back, maybe it was BJ, that an 8 or 8 1/2' blade will do even better. I bought what I thought was a good miter blade for a Makita chop saw for $60. I found out that you have to spend a lot more than that for a really good one. I also found out that you can improve an average blades performance significantly by using blade stabilizers. Even Forrest recommends them for their blades.


I read his post ... that he used 6-1/2" blades. I bought some to use in my Rockwell TS... and darn if he wasn't right. Very smooth fine cuts. I started buying up 7-1/4" finish blades.

I have some 8" blades, but for some reason 8 to 8-1/4" finish blades are atrociously expensive...


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## greenacres2 (Dec 23, 2011)

I ended up doing it last night...Home Depot had the DW718 (actually DW718SP for Special Pricing) at $399 in store only. LOML drove me over, I knew the box would fit in her car--wasn't so sure about mine. Talked the dept manager into $20 off since it was going to cost me a burger for my Bride's driving. Out the door at $379 plus tax. 

Thanks for your comments Mike--your mention of blade deflection months ago was already in my mind and had been another reason for focusing on the 10" to start with. I don't do a lot of molding, and transport to job site isn't an issue so i'm hoping it was a good move. When we got to HD last night, I really waffled on picking up a Ridgid 10" instead. Same money, 12" depth of cut, Freud 40 tooth (which i'd have moved to the table saw and put a Freud 60 tooth on the SCMS). Then again, at $400 Ridgid would not have been too far from a Bosch 10". I respect the Ridgid lifetime service thing but I gotta say--the Ridgid 10" was displayed next to a DW780 and there was a significant difference in the construction, the way the miter table moved, bevel adjustment. 

The saw is still in the box--i'm going to let this settle for a day before taking it out. Excellent point on the blade stabilizers, remembering that as an option may ease some of the anxiety of the potential for blade flex. 

Now it's time to clean up the RAS and the old miter saw to get them ready for their photo shoot. And time to decide whether I want to put the new miter saw on the table built for the RAS or on the folding stand I have. Thanks again!!
earl


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## MAFoElffen (Jun 8, 2012)

Congrats! You'll be happy.

Check the tune. (Adjust the fence and the stops.)

A couple notes on your post-

Miter Saw and RAS Blades have significantly less hook angle on the blade teeth than table saw blades. Most fine finish blades for miter saws have a negative angle, which if used on a table saw, you'll notice you more effort getting your work pushed into the blade. It will work, but the feed rate is slower. If you use them on a TS, you'll also have to clean them more often than on a miter saw. The buildup collects quicker if using it on a TS. If you use a 10 TS blade on a sliding miter, you just have to watch that you don't feed the blade too fast.

On blade flex, you made the right choice. No worry's. Lots of various types blades available for a 5/8" arbor (10" and smaller) everywhere. I have problems walking in somewhere and finding a 12" blade that is for a TS!!! Most all in stores are for Miter Saws... that negative hook angle issue. Ordering is fine.


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## harrysin (Jan 15, 2007)

greenacres2 said:


> Over the past few months I've been considering replacing my RAS (Craftsman, circa 1988 with recall kit, purchased used) and miter saw (craftsman, 10" bottom of barrel, purchased new in 1993) with a sliding CMS. The RAS is used almost exclusively for cross-cuts to right at 12" and the occasional dado, but I've been doing most of my dados on the table saw or with a router. The miter saw just isn't accurate enough for anything beyond rough framing if that--never really has been, but I now i'm aware of it.
> 
> I've built up a pretty good collection of 10" rip and cross-cut blades, so I was thinking that a 10" slider with 12" cross-cut would not lose any ground and i'd be able to interchange the 60 tooth blades between table and slider. Mitering would have to get better than what I've had, no way to get worse.
> 
> ...


Earl, within the next 24 hours I will be making the decision whether to buy the Bosch GCM12GDL which I wish was at the same price as that which you quoted. The best price so far here is $A1060.00. If I do decide to plunge I shall be keeping my Radial arm saw which I couldn't live without.


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## Cherryville Chuck (Sep 28, 2010)

harrysin said:


> Earl, within the next 24 hours I will be making the decision whether to buy the Bosch GCM12GDL which I wish was at the same price as that which you quoted. The best price so far here is $A1060.00. If I do decide to plunge I shall be keeping my Radial arm saw which I couldn't live without.


I drooled over one earlier this week. They appear to be a well made, well thought out machine, selling for $699C at the closest big orange box store here which is quite a bit cheaper than they were a year ago.


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## OPG3 (Jan 9, 2011)

Earl, you made a good choice and set-up permanently (as opposed to travelling job-to-job) it should last you forever. My SCMS is a Makita LS1013 and I love it. My prototype work doesn't have to be pretty - just super-accurate angles and dimensions, but this saw would be great even for beautiful trim work. I've had it about 10 or 11 years and have never needed to replace anything except those little plastic inserts along the sides that are designed to be occasionally replaced and are inexpensive.

Staying with 10" blades (which match my tablesaw) makes things simple for me.

Otis Guillebeau from Auburn, Georgia


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## carlp. (Nov 3, 2012)

*sliding compound mitre saw*

Harry have a look at the bosch I bought a gcm 10 sd 3 years ago and no adjustments were needed it is spot on right out of the box on bevels and mitres. regards carl


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## Mike (Nov 22, 2004)

Carl, Harry bought the saw and loves it. Bosch recently introduced a 10" version.


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## harrysin (Jan 15, 2007)

Mike said:


> Carl, Harry bought the saw and loves it. Bosch recently introduced a 10" version.


I sure do, it has replaced both my cherished 10" DeWalt radial arm saw and Makita 10" compound mitre saw.


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## OutoftheWoodwork (Oct 4, 2012)

harrysin said:


> I sure do, it has replaced both my cherished 10" DeWalt radial arm saw and Makita 10" compound mitre saw.


Harry, you lucky dog, you! Wish I had the cash to get one! I saw the Bosch 12" 
last year at this time and was wishing for one (posted about it here, too lol) Now 
they have the 10" out, and I'm even more anxious to get one. Although I really 
think I would rather have the 12". What's the widest size board you can glide through?


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## harrysin (Jan 15, 2007)

I reckon a little over 14" Barb. Have you given any thought to asking Mike to share his new one, possibly alternate each week!


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## DaninVan (Jan 1, 2012)

Mike; yeh, I've also found that 81/4" finish blades aren't that easy to find. For that matter, neither are the 81/4" saws. Not that they aren't available, rather that they aren't prominently displayed.
I shouldn't complain though, I pity the poor soul who's trying to locate a left hand builder's saw!
(I may have mentioned a couple of weeks ago that while in at Summit Tools, I found they had literally _ hundreds_ of el cheapo 71/2" 24 tooth carbide blades, but not a single 40 tooth version(?)! )


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## MAFoElffen (Jun 8, 2012)

DaninVan said:


> Mike; yeh, I've also found that 81/4" finish blades aren't that easy to find. For that matter, neither are the 81/4" saws. Not that they aren't available, rather that they aren't prominently displayed.
> I shouldn't complain though, I pity the poor soul who's trying to locate a left hand builder's saw!
> (I may have mentioned a couple of weeks ago that while in at Summit Tools, I found they had literally _ hundreds_ of el cheapo 71/2" 24 tooth carbide blades, but not a single 40 tooth version(?)! )


 I have an 8-1/4 circular saw. I have a good line here on 8" to 8-1/4" blades. But, all that I've found locally are higher in cost than 10" blades. Probably because they are less common? But that is from a commercial tooling shop here.

7-1/4 inch... common as all get out in 24 tooth through 60 tooth. Here, even Home Depot and Lowes sells Frued 7-1/4" blades in 40 and 60 tooth (finish). Same with 24 tooth 5-1/2" and 6-1/2" blades... Hey, this keeps coming up, so I thought I would explain this so there is more of an understanding to what "total tooth count" really translates to between blade sizes... (forgive the momentary off-topic, but it gets back to it...)

Dan- I don't use that Circular Saw anymore, but I use all those sizes of blades on my table saw. They are all 5/8" arbors. Some of them I got cheap because they were an offsized arbor, which I then bored to 5/8". They make cheap miter blades for the RAS and table saw. The 8-1/4" blades, I don't tend to use often, because they cost so much!

But 60 teeth on a 5-1/2" blade diameter equals a lot more "teeth per foot" than 60 tooth on a 12" blade. To see what I said really means, lets do some tooling math. The math says: (If you don't care how to figure it out, then just skip to the summary...)

Circumference = Pi x Diameter 
3.14 x 5.5 = 17.27 
3.14 x 6.5 = 20.41
3.14 x 7.25 = 22.77
3.14 x 8.25 = 25.90
3.14 x 10 = 31.40
3.14 x 12 = 37.68

Here's where this starts to make sense in something that you can compare with:

Distance between teeth = circumference / total teeth 
12", 37.68 / 80 teeth = 0.47 or 25.53 teeth per foot

Comparable Teeth count for a blade size = Circumference / Distance between teeth
Example for 10"--> 31.4 / 0.47 = 66.8
10"... 66.8 teeth
8-1/4"... 55.1 teeth
7-1/4"... 48.4 teeth
6.5"... 20.41 teeth
5.5"... 17.3 teeth

Summary:
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So a 24 tooth 5.5" or 6.5" blade is comparable in "teeth per foot" to a 40 tooth 7-1/4 blade, a 60 teeth 10" and an 80 tooth 12" blade...

As you get smaller in diameter, because the radius is smaller, the blade seems stiffer and you get less blade flex. Because the circumference is less, you don't need as many teeth to translate into the same thing. And because they are not commonly thought of as being better in quality and have flooded the market for tooling up rechargeable and mini circular saws... they are dirt cheap. Drawback is you don't get as much depth of cut... But if you do need that, put on a bigger blade for those and change it back out. (I do that anyways. My saw has the capacity for 12" blades, but has a 5/8" arbor. For my 12 blades, I use either 30mm to 5/8 or 1" to 5/8" bushings.)

Heck, most of my cuts are less than 1-1/2"... actually most are 3/4" and less. I can use a 5-1/2" blade with blade stiffeners for most trim cuts on a table saw and RAS... But not true for a Miter saw. With a miter saw, it depends on where the stops can adjust to. The head will only go down so far. With a smaller diameter blade, you hit the stops.

Everyone I know in the business who had 8-1/4" or 9-1/4 saws traded them out. Just too hard to find blades for them and they got pricey.


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## DaninVan (Jan 1, 2012)

They'll have to tear my DeWalt 8 1/4" out of my rigour mortised fingers! 
Last week I gave my old Makita 8 1/4" to my son-in-law, with two resharpened 8 1/4" blades and one of those el cheapo 7 1/4(?)" (...why did I think it was 7 1/2"?)

As for the 10" Bosch SCMS..._me want!_. I was working in a tight space with my old Bosch SCMS last week and that extra space requirement was a real headache.


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## Cherryville Chuck (Sep 28, 2010)

Mike, while there is a difference between the tooth spacing on different diameter saw blades I would think that the rpm would make more difference. If you have a 12" blade with 24 teeth and a 5.5" 24 tooth blade and they are turning the same rpm there will be an equal number of cuts per minute. However, most small blades are turning faster so they will make more cuts per minute. I would change your calculations to rpm times #of teeth. The gullet capacity can have an effect but that is covered with feed rate.


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## MAFoElffen (Jun 8, 2012)

Charles-
Thanks for reminding me of that. What I was told previously, was that you spin blade so that your surface feet per minute (sfpm) is between 10,000 and 18,000. That is supposed to be optimum for wear and quality cuts. 

My saw spins 4000 RPM on the main and 8000 RPM on the scorer... so it hits that mark down to 9 inch blades on the main, but falls short on blades smaller (8.5 to 6.5")... I thought this was a problem, until... I started looking up specs on new saws with those sized blades, then figuring out the sfpm for those saws new... and they fall between 6500 sfpm and 9000 sfpm. So figuring out the math on what I was getting compared to those, they still are fairly close to that. They were withing 200 sfpm to the saws they were meant for...

I found a new online calculator for that, that I posted that in the online calculator section here:
http://www.routerforums.com/dynamic...lar-saw-blade-sfpm-calculator.html#post363584


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## Cherryville Chuck (Sep 28, 2010)

I can't remember what my saw is turning but I think it is around 4000 which would put it at the low end of your calculation. The calculator reminds me oaf a formula I've seen for calculating feed speed on sawmills. Back when I first moved to Cherryville there were a bunch of small sawmills. Almost all of them were using 52" head saws which they ran at about 550 to 700 rpm. One saw miller told me about the formula so that you could calculate the pulley size on the feed works for maximum cutting capacity. Most saw millers didn't worry about it. In big logs they were down to maybe 6"/sec feed rate to keep the rpm up and also not heat the saw blade. I've seen those saws get hot a few times and they start to wobble up to 2" back and forth till they cool back down. I was always taking boards and timbers off the carriage and I didn't like being on that end when the blade started doing that.


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## OutoftheWoodwork (Oct 4, 2012)

harrysin said:


> I reckon a little over 14" Barb. Have you given any thought to asking Mike to share his new one, possibly alternate each week!


Yeah right Harry. You're a riot :lol:


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