Are SCMS accurate enough for fine woodworking?
Hello, I’m looking to purchase a a sliding compound miter saw for wide crosscutting and miter cuts but I’m wondering if they are considered accurate enough for fine woodworking. Every one I’ve ever tried at the store always seems to have a little blade deflection when fully extended. I had a Makita LS1016 for a week (had two actually) and they had a lot of blade wobble and when fully extended, they would move up to a 1/16th either way which led to wobbly cuts on wide boards. Needless to say, I returned those saws.
So right now, I’m looking at the Bosch 5312 or 4310. They both have good reviews but I’ve also read that some people consider sliders only for construction purposes. I’ve also heard that 10″ is more accurate than 12″ sliders.
I really don’t want to use a huge sled on my table saw for wide cuts anymore. I’d rather get a SCMS if they are accurate enough. Does anyone have any advice on these saws or on SCMS in general?
Replies
Absolutely they are accurate enough, as accurate as your eye can see. If you extend any of these saws, you probably can get them to move but that is not what you are supposed to do when you use them. The saw you used may have been worn, a bad bearing, out of adjustment or had a bad blade. Tuned up and with the proper blade most of the better SCMS are dead on, including the Makita.
I use an older Bosch 10" and I won't use thin kerf blades, I like the Freud negative hook blades but I'm not sure the ones I use are still available. Often the factory blades are just so so. In addition to cabinet and furniture I trim a lot of houses. This involves cutting things that are too large or too long for a table saw, things like hardwood crown moldings, stair rails and parts. Many times the pieces are prefinished so there is no sanding, the cuts have to be right on.
SCMS have only been around since the 80s. There are now many manufacturers and their quality keeps improving, 10 or 12". They are a great addition to any workshop and invaluable for on site work. Here are just a few pictures, I think these are accurate but your eye may be different.
How, how, how?
As in, how accurate is accurate? How "fine" is fine woodworking? How much of the saw's accuracy depends on the operator? ;-)
I don't own an SCMS, mostly because I feel the tubes used for the sliding mechanism are too light weight and allow too much sideways flex during operation. That is to say, too much of the saw's accuracy depends on the operator - if you pull to one side during the slide, for example, the accuracy of the saw will be compromised. The design of the new Bosch "glider" (with the knuckle joint instead of tubes) may solve a big portion of that. I haven't used one, though, so I'm not sure.
The Euro-style sliding table saws offer another approach to providing accurate cuts, but at considerable expense - both in terms of initial cost and in floor space required.
I have an old Delta 12" radial arm saw that doesn't flex, and stays accurate for 90° cross cuts. But, it's a little scary on angled cuts of any sort.
But, I also tend to agree with Hammer - if you avoid the so-called thin-kerf blades, and use the right technique, a good SCMS or GCMS (glider) is probably accurate enough, particularly with long stock that would be difficult to manage on a conventional table saw.
Then, there is the school of thought that saws make rough cuts that should be refined with a shooting board and a good plane. This allows you to make sure the end of the board is dead square, and adjust the length by thousandths of an inch.
In the end, I think it is a personal choice, and one that should consider how you work, what you make, the size of your budget, and the size of your shop.
SCMS
The very best CMS is the Festool Kapex. Used to demonstrate it at the store.
Though it doesn't slide. The metric equivalent 10" blade will cut what a 12" blade will cut, due to its design.
Sliders are used by every professional trim and finish carp and accurate cuts and tight joints are often just as tight as any furniture if that's what's required. The best trimmers I've ever worked with like the 12" Makita slider. More than one cabinet shop has a 12" dewalt since it can cut a full 16", although the one I had wasn't as repeatable as I'd like and it was heavy. Of course the Festool is used by many top finish carpenters who don't mind spending big bucks.
When someone is talking down on sliders the first thought that comes through my head is they are using cheap blades that are much more prone to wander on a long cut. Skip the thin kerf blades and, at least in my experience over the last 15 years, get a couple of Forest blades and you'll learn to love whatever saw they are on.
The second most common reason sliders make crappy cuts is a lack of understanding of how to fine tune the saw. The slider bearing can't be allowed to loosen up, the bevel and angle adjustment,s and indicators have to be dead on. The fence has to be true and the bed has to be flat.
Of course overall it's opperator error that is most to blame. I honestly don't care if a saw can deflect 1/16" with pressure to the side - I'm more interested in how repeatable and consistent it is with a deliberate careful cut. Learning to use a slider includes using that deflection to your advantage whenever possible. If you need a dead accurate 45 degree cut I will often put a very slight side pressure on the first cut leaving what I know will be a hair less than 45 degrees and then follow up with the correct amount of pressure or no pressure at all to be dead on. Having said that if the material being cut has been flattened, trued and straight as can be it's more likely that the saw is simply adjusted to be dead on with no user-applied english.
I think of a slider the same as a simple chisel - there's a lot of art to using it to it's full capacity. If I was given a choice between a slider and a festool track sawf for super accurate long cuts I'd take the track saw every time. When they are fine tuned and sharp the cut is glass smooth and splits the finest of pencil lines. They are slower, but dead nuts on if you simply point it in the right direction.
In a cabinet shop it makes more sense to have large crosscut sleds and whatnot, but for 99 perect of woodworkers both hobbiest and professionals the portable tools give a lot of bang for the buck.
Well, I decided to try out the Bosch 4310 and yet again, I was left disappointed. The problem with that saw is that they use a plastic lever for their detent system which would flex quite a bit and allow the saw base to move a couple of degrees either way when it was in its detent. I would rotate the saw to 90 and I couldn't be sure if it was dead 90 or 88, 89, 91, or 92. It would vary each time due to the slop in the detent system.
I called Bosch about it and even made a video showing the issue and they said it was normal. For $500 I don't think that should be "normal". I've tried other saws and their detents were rock solid and there was no doubt the saw was locked into that angle. So I guess I'm returning another SCMS.
I'm really not sure what brand to try next. I'm not even sure I want to try another SCMS. I seem to be excellent at finding lemons.
Wide Cuts
I would buy a radial arm before a sliding chop saw. I don't have either. A couple of years ago I had to build a large crate on site for a client. My PC 10" wasn't big enough. I made a jig - don't remember where the idea came from but it does the job. My Dewalt rides on the top of two tracks - you can make this as wide as you want and it's a stationery tool.
SA
SCMS
In my furniture & cabinet shop I have a RAS a chop saw and a Makita scms 10" .
The larger the blade the more deflection , so for accuracy smaller is better .
Don't confuse the scms with being able to crosscut large panels . How large of miters are you going to make ?
regards dusty
I would like to be able to crosscut boards upto 12" without having to break out my huge sled all the time. I'd also use it for trim work, general miters, etc. but those usually aren't more than 6" or so. It would be nice to be able to do some quick dados on the occasional sub 12" board also. There are lots of instances where I find my current small miter saw just isn't big enough and wish I had a slider. I just can't find the right one. There seems to always be some major flaw in them that I won't put up with. Not for that kind of money anyway.
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