How square should a SCMS cut?


WoodNoob
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Hi again folks,

How much in accuracy do you accept from your tools?

I ask because I have an entry level sliding compound mitre saw from Bosch and it's never cut square. It's a combo of factors, cheap inaccurate fence, indents that are a little sloppy, and probably rail or blade deflection on longer cuts.

I've taken it back to the place I bought it and Bosch took it away to their shop, tested and tightened it and brought it back. It had a note on it saying they had tightened everything, remeasured all the indents, tested it for square. I took it home and on my first cut could see it wasn't square. It was about a mil out along an edge about 15cm long (1/32 over 6"). I can almost see that with my eye (it may have been a little more), and I can certainly see that against my square. It was a lot more out along a longer cut. In addition, every time I reset the fence to zero degrees, I have to get my square out to check if it's right on zero. Is this acceptable? I think I'm going to take it back again.

I know that firstly it's entry level and secondly SCMS aren't know for accurate fine woodworking. But I feel like the one thing it should do is cut pretty straight without too much fussing. I feel like entry level means perhaps it won't last as long, will have shorter and shallower cutting capacity, noisier motor, etcetera. But the basic requirement is a straight cut...?

Thoughts?

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I've used numerous scms's and only one cut square (that was a Makita). Even the Makita had to  be checked regularly and adjusted. My advise is to take it back and get a standard cms. How accurate should it be? I'd say you need to answer that question for yourself. For me, I want it dead on.

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I'd take it back.   I don't know if it's a fluke, but my 7 year old Dewalt has never had to be adjusted any kind of way, and it's still dead on. I just checked it a couple of days ago.  It doesn't get drug around a whole lot.  Even though it's accurate, the most precision stuff it cuts is trim in a house.  Otherwise it just cuts to rough length.

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You don't need to spend that much money on a miter saw. If you can then go for it, but its not necessarily going to take it to the "next level" for you, it's a miter saw.Precise cross cuts are normally done on the ts in most cases, for me anyways. I don't use my miter saw for finished cuts in my furniture or cabinets anymore. I install crown moulding on kitchen cabinets all the time and I own a bosch glider.  It's not the saw, it's the person using the saw. If you don't adjust your saw it won't be accurate. We bought a 100 kobalt beater to bring to job sites. I set it up and it cuts just fine, and you can carry it in one hand. In short, I would not spend $1350 on a miter saw, you can buy a bosch, gravity stand and have money left over for a good blade and some wood to cut. 

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Yeah, I feel like a standard CMS would stay accurate longer for sure. The reason I got a slider is for the times I don't have access to a TS and want a wider cut. But still.

I'd loooove a kapex, but you know I need to eat ;) it's on the list though.

I'm pretty confident it's not just me. I've tried adjusting the fence (it has very little adjustment), I've done the five sided cut test, I have an accurate square to set it up checking against one tooth from front to back. I just think it's got too much play in the system. Yep I think I'll take it back again.

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I've used a miter saw where the blade shuttered when running. I'm not sure if there was a bad bearing, bad arbor, bad blade??? Even with all adjustments made there was no way that saw was going to cut consistently. when your saw is running is there any "shutter" in the spinning blade? Is your fence straight? My fence is 2 seperate pieces on my bosch glider, I had to shim to get them in plane with each other. 

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Yeah I think that is the bottom line. I'm just bummed that there's no replacement at its price point. I'll either have to save up some more to replace it or put that money towards something else. It's not a cheap hobby we've chosen!

Shutter? Shudder? Like does it vibrate? Potentially a bit, not really noticeable. But it does have a hard start. So it takes off like a bucking bronco when you pull the trigger. No soft start. So I bet that knocks it out every time.

Its a single piece fence but not super accurate. I think it's just too cheap for what I want.

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I have the Dewalt 12" SCMS and I'm able to adjust it exactly to 90 or whatever angle needed.  10 years ago I had a Craftsman 10" compound miter saw with a cast iron table that I also was able to adjust accurately but it was not a slider.  Perhaps a saw like the Craftsman would fit your needs until you can afford the Dewalt or a Festool. 

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I am going to be the big jerk here and question your practice. Do you let the saw run up before initiating your cut? Do you let the saw come to a stop at the bottom before moving it? Also, what kind of blade and how sharp? Sliders are the most finicky in economy saws, especially over wide widths, but those other factors on some saws will make it worse in a hurry.

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I am going later today to look at another kitchen job, where I will be installing the crown after the cabinets are installed. This means I will be checking my adjustments this weekend before I bring my saw back out to the job. Only reason I am checking is because I have brought the saw around to many jobs doing flooring framing trim, you name it, and gone through blade changes. Pre finished crown is about the only thing I am fussy about with my miter saw adjustments. 

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Personally, I've got a cheapo cms that cuts dead on 90 as long as you don't tighten the lock screw, it throws it of 2-3 degrees? If I need a nice square cut in stock to long for the TS, I use a rafter square and a circular saw, it doesn't matter how you get there, just as long as its square when you get there...

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The amount of 'accuracy' you should expect depends on what you do with your saw, how you care for it, how willing you are to check settings, perform maintenance, etc...

 

First of all, I currently own three CMS -- two sliders (Kapex, DeWalt 805) and a twenty-year-old Makita CMS (a classic).  Over the years, I've worn-out another DeWalt and a Bosch...

 

For over fifteen years, I never used a SCMS for furniture --- as mentioned by many, most are not 'accurate' enough.  I carefully adjusting my DeWalt and Bosch prior to starting a furniture project, but found that they wouldn't hold their settings by the end.  Sure, I could get 90 and 45, but then I'd need a 22.5 and it just wouldn't dial-in, so I'd readjust to get the intermediate and then the 90 wouldn't dial-in -- what a pain in the ass...  Or, if they were properly adjusted, there was just too much play in the mechanism to deliver what I needed.... So I developed a TableSaw-centric cross-cut workflow --- it was easy, I had a Felder and the slider makes it a no-brainer...  The SCSM was relegated to DIY...

 

Roll-forward a decade, the Kapex is introduced to much fanfare...  I did the 30-day trial... and kept it... It's certainly proved accurate enough for furniture and has held its settings for over a year without any adjustment... I use Forrest Signature ChopMaster blades on the thing (blows-away the FT blades)...  But here's the rub -- it doesn't leave my shop, doesn't see pressure treated lumber, decking materials, aluminum gutters, etc...  In short, it's dedicated to 4/4 or 8/4 dried S4S material (I kept the DeWalt for DIY)...  In short, the Kapex is not stressed in my shop, so I don't know how it would hold-up if used heavily...

 

From my experience, if you want a SCMS for furniture work, you're going to have to spend the $$ -- I've never seen an value-proposition SCMS that consistently holds its settings or doesn't have excessive play... or require checking/adjustments for every project... I've used the new 10" Bosch and it's also a keeper (it's certainly cheaper then the Kapex, but still not cheap).  Alternatively, you can go a bit cheaper if you are willing to check your settings regularly...  Some folks are good at that... some aren't (that's me)... 

 

Alternately, if you want an SCMS for site work/DIY/etc and furniture, then I think you need two saws (one DIY and one Furniture)... You could get either two SCMSs or one value-SCMS for DIY and use the TableSaw for furniture...

 

I like my Kapex and folks report that it holds it's settings in the field -- but I don't know -- one or two good bangs in the truck and I bet it wont...  I know a high-end trimmer/finish who uses the Bosch in the field and loves it...  But he replaces his SCMS every year --- or when it shows the least amount of play -- whichever comes first ... I think it's just the nature of the beast...  He takes two SCMSs to the site -- one is for final finish work and the other is for the rough cuts...

 

But if you want to use an SCSM for furniture, then you need a good blade -- full stop...  These $49.95 box-store specials are not your friend...  Keep those for framing...  Spend the $$ for a decent blade -- you will be surprised at the difference...

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==> Just for kicks i made this test cut on some 8/4 maple on my 10 year old Bosch SCMS, which has been used and severely abused. The board is about 8" wide.  I edge jointed one edge but it has not been face jointed.   It looks perfectly square to me. 

 

I never had any issues dialing-in 90/45 on my Bosch or Dewalt and keeping it there...  The issue for me was when I started looking at the work of folks like David Marks and modern design in general --- angles like 7, 83, 38 or 52 degrees frequently come into play... That's where I ran into trouble...  I could get 45/90, but the rest would be +- a degree or so...  That's when I switched to the TS...  When I got the Kapex, I could dial-in any angle and it's spot-on.  Same for the new Bosch...  But if I kept them in the back of my truck, well...

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I don't own a sliding CMS.  I have a 10" non-sliding CMS.  It only ever gets used for rough work now.  There is just too much play between the indentations for the hard stops that its hard to know if it is square without checking it.  It also seems like it falls out of square too easily while working.  Between a cross cut sled, and a incra miter gauge, I get far better cross cuts on the table saw.  I have had people ask what I do about longer stock.  The longest I have had to cut was around 5', and the sled made it very safe and easy to make that cut.

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==>  I think we all agree that if the saw can't cut square it should go back!

 

absolutely...  if you can't get 90, 45 and the other standard detented angles, then it should go back...

 

 

==> Here is a picture of that project with my apprentice helping out. 

nice...I have to be careful about leaving images like that around -- they automatically become honey-do items...  After all, it's just a bench, isn't it :)

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==> like the omga are the cheapest alternatives

When we building our cleanrooms, the contractors brought these bad boys on site...  I had never seen one before and was quite interested --- until they told me the price...  These were the 3hp versions and I think they started at about $5K...   But they had custom blades for cutting honeycomb aluminum...  These things weigh like 150lbs... 

 

But back to reality -- I think a Kapex is just about the max anyone is willing to spend...  And even that's a push... Afterall, a Kapex + UG stand + extensions + CT Vac + Forrest Chopmaster is what, $2,700?  God, hope my wife doesn't find this post... :)

 

 

 

==> You won't get perfect cuts long term with a universal motor direct drive saw. 

Agreed, but I'm assuming folks are interested in CMS/ SCMS for hobby/single-man-pro shops...  If they dedicate the saw for furniture and it doesn't leave the shop, I'd hope to get ten years out of it...  One other thing, the Kapex is certainly not the most robust piece of kit in my shop, so I am quite careful with long/heavy stock around it...  I bet one or two serious bangs (like the kind that leave dents in my ductwork) would shorten it's 'accuracy-life' rather quickly... 

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==> like the omga are the cheapest alternatives

When we building our cleanrooms, the contractors brought these bad boys on site...  I had never seen one before and was quite interested --- until they told me the price...  These were the 3hp versions and I think they started at about $5K...   But they had custom blades for cutting honeycomb aluminum...  These things weigh like 150lbs... 

 

But back to reality -- I think a Kapex is just about the max anyone is willing to spend...  And even that's a push... Afterall, a Kapex + UG stand + extensions + CT Vac + Forrest Chopmaster is what, $2,700?  God, hope my wife doesn't find this post... :)

 

 

 

==> You won't get perfect cuts long term with a universal motor direct drive saw. 

Agreed, but I'm assuming folks are interested in CMS/ SCMS for hobby/single-man-pro shops...  If they dedicate the saw for furniture and it doesn't leave the shop, I'd hope to get ten years out of it...  One other thing, the Kapex is certainly not the most robust piece of kit in my shop, so I am quite careful with long/heavy stock around it...  I bet one or two serious bangs (like the kind that leave dents in my ductwork) would shorten it's 'accuracy-life' rather quickly...

I returned the kapex it was ok but not tight enough for cabinet doors. Like all festool products they are job site tools.

The 3hp omga's are not even close to $5k somebody was blowing smoke. The 2.2hp 12" is $2300 and more accurate and more powerful than the kapex but is just a cms. The 14" 3hp is $3600. Those are full list prices usually they can be had for a few hundred below list. Nether are jobsite saws they only come in 220v single or 3 phase. I got my 2.2 for $1950 new. They are the saw of choice cabinet shops on a budget doing mitered doors.

Direct drive saws rely on the motors which get run out after very few uses and they have end play. Induction saws have arbors on par with a 3hp and 5hp tablesaws. Any end play or bearing runout even the slights bit screws up your miter cuts. This is why people struggle with even better saws. Vibration does weird shi& to your blade.

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