Is smoother really better for a saw or jointer top

[Rob Blaustein]

I've read various posts in which people proudly talk about their polished and glassy smooth tops on their jointer beds or tablesaw tops, and when my own tablesaw arrived, I was impressed with how smooth its top was. So imagine my surprise when, at the recent WW show in in Springfield MA, I got to actually touch one of those beautiful (and expensive) Minimax combo machines, only to find that the beds and saw top did not feel as smooth as my own saw, but rather had kind of a finely etched pattern to them. So I asked the rep about it, and he explained that a perfectly smooth top actually created more friction since more of the top was in contact with the piece, and that having these very fine ridges made the wood slide more easily. That does make sense to me, from a physics perspective, but I hadn't heard this before and was wondering if others had, and what people thought about it. Do you Minimax users notice this on your tops, and do they seem to offer less resistance?
-Rob

[Matt Meiser]

I haven't seen the Minimax in person, but I do know that I just cleaned my top with 400 grit sand paper and then a green scotchbrite pad and heavily waxed it and things glide through the saw much easier than before. I wonder if they are refering to what I belive is called "stiction" where two very flat smooth surfaces will actually stick together? Sometimes you notice this when attempting to separate two pieces of glass.

[Steve Cox]

My Laguna bandsaw has a very rough surface to it and things seem to slide just fine. I keep my tables waxed but usually pay very little attention to "ultra smooth" claims. The wood just needs to slide smoothly

[Jim Becker]

The nice thing about the type of grind on the Mini Max combo j/p I have is that the wood doesn't stick to it once it's flat and smooth. It's certainly not as pretty and you can't use it as a mirror to shave (and I'd like to keep sharp blades away from my flesh in the shop, thank you very much... ;) ) but it absolutely excels in keeping friction to a minimum as you process stock. Matt's description is right-on about the "problem" with super polished surfaces and it's especially fun when you have the ability to process wide boards....that can be a lot of surface area to "stick" to the tables.

I still wax my tables, but primarily to keep them from rusting.

[Bruce Page]

Rob, as much as I like my MiniMax bandsaw and the folks at MM, I think the sales rep was blowing a little smoke. I agree that from a “physics perspective” it does seem logical. On the other hand, I think that if you took two smooth, waxed table surfaces, say a MM combo, and a PM66 and measured the drag coefficient of a flat piece of oak being pushed across each, I think the difference would be indefinable, especially to your arm. Also, most high dollar machine tools have highly ground tables, some in the 6 - 8 RMS range.

[Doug Shepard]

It's not a totally new theory. The same thinking is behind corrugated sole planes supposedly reducing sticking caused by a vacuum. So I suppose he might be onto something.

[Jim Barrett]

I had a MM combo machine and did not particularly care for the blanchard grinding on the tables. I found the material did not glide over the table as well as my new smooth finished jointer and table saw.

Jim

[Dale Thompson]

Hi Rob,
In terms of pure physics, frictional resistance has NOTHING to do with the area of contact. It is calculated based on the FORCE of contact between two objects and the empirically calculated coefficient of friction between those two unique objects. :cool: As a matter of fact, two pieces of red oak could have a slightly different coefficient of friction with the surface of your table saw, etc.. With woodworking, we can ignore the "Wringing" of two micro-finished surfaces which can create an inseparable joint. That is a molecular exchange which is not a factor in our hobby. ;) :eek: In other words, there is no such thing as a "too smooth" board and a "too smooth" table top. :D

From my point of view, I would prefer the "mirror" finish on my PM66 (AHEM - It's not like that anymore :( ) over the "beaver chewed" finish on the top of my Delta Oscillating Spindle Sander. Realistically, however, the "beaver" finish is not all that bad. It can only be assumed that a rough finish on a table top can be translated into a high micro-inch measurement on the table top. That WILL result in an increased resistance for ANY material traversing the surface. :eek: :) What did I just say? :confused:

I only wish that "pushing" resistance was my biggest problem in woodworking. How do you spell KLUTZ, INCOMPETENCE, and SCRAP??

Dale T. :)

[Dale Thompson]

I wonder if they are refering to what I belive is called "stiction" where two very flat smooth surfaces will actually stick together? Sometimes you notice this when attempting to separate two pieces of glass.

Matt,
I think that the glass dilema is a bit different than the "wringing" effect. With two pieces of glass, you have equal atmospheric pressure acting on both sides of the glass panels. Since the glass is "relatively" smooth, there is very little air between the surfaces. When trying to pull them apart with a purely tensile force, you are, in effect, creating a vacuum. Nature abhors a vacuum and therefore resists your efforts - sometimes to the point of fracture. :eek: :eek: We can't mess with Mother Nature! :D :)

Dale T. :)

[Paul B. Cresti]

Rob,
I have owned both types of cast iron finishes and most definately 200% prefer the blanchard finish of my current MM machines. I hated the mirror finish as it would show every possible pit, scratch,etc.... I have had not one bit of problem with sliding at all and I get some pretty big pieces of stock on a 16" j/p. I too keep all my cast iron surfaces coated with paste wax. FYI the blanchard finish is the more expensive finish. Most manuf. do not like to do this type of finish because it can take the better part of 1/2 day in order to achieve the blanchard finish on a large bandsaw table. Another reason European machines are generally more expensive. The mirror finish is something that the American market prefers (except for me that is...and some other people I suppose :) )

[Alan Turner]

I have the "rough" finish on both my Aggazanni BS and my old 1920's jointer, and they present no problems. This is not somehting that I worry about as there are far too many other things more dederving of my worriment.
Alan

[Norman Hitt]

I find it real interesting that when I bought my PM-66 14 yrs ago, it Did Not have a mirror finish on the table, as they apparently are today. I figured they polish them now, because it is either a cheaper process, or strictly for sales appeal. It was not a true Blanchard grind like my MiniMax tools, but it did have the same curved grind marks over the whole top, and all grind marks were shallower and basically the same depth, not variable like the Blanchard grind.
After many years of light sanding with scotch brite pads and useage, most of the marks are now gone, and with equally waxed surfaces, it seems "slightly" easier to slide a board across the tops of my MM machines (not running/still no power, just dreaming) than the PM-66, so I really have no answer to this question, as there's just not enough difference to count.