RAS Versatility


This is an extension of the earlier post regarding RAS's and Miters Saws. How about RAS versatility? It will do crosscuts, and rips, and miters and dados. How about bevels? Anything else? Is there any reason not to do dados on a table saw? What make the RAS an inferior tool for ripping?
Joseph
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Joseph Handy (in snipped-for-privacy@corp.supernews.com) said:
| This is an extension of the earlier post regarding RAS's and Miters | Saws. How about RAS versatility? It will do crosscuts, and rips, | and miters and dados. How about bevels? Anything else? Is there | any reason not to do dados on a table saw? What make the RAS an | inferior tool for ripping?
There's no reason not to do dados on a TS. I've found that _angled_ (diagonal) dados are somewhat easier on my RAS than on my TS; but I use whichever seems to best fit what I'm doing.
The RAS doesn't normally have a splitter that keeps ripped wood from pinching the blade.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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My old Craftsman did, and anti kickback pawls.
said:

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Crosscut dados are much easier on the RAS. Rip dados are much easier on the TS. For the same reason crosscuts are easier on a RAS and ripping is easier on a TS.
RAS will do anything a CMS will do, but is awkward to set up. I would not have gotten rid of my CMS if I did many. However, the RAS will do many things a CMS will not do, like dado. But it will also go into positions that can only be done with a RAS, like horizontal cuts. I have not had occassion to do any of them, but might someday.
Ripping is undesirable for several reasons. You are restricted to a 19 wide cut. The table is not as big, so support can be a problem. You are working with MDF instead of cast iron and steel/aluminum, so it just doesn't work as well. But the biggest problem is with kickback, which is much worse on a RAS than a TS. It's just a bad idea.
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Joseph Handy wrote:

Sure. _____________
There are tons of accessories for them...sanding disk plates, sanding drums, router collets, molding heads, soft sanding pads, rotary planers, etc. Some work well, others don't. _____________

It's not so much that it is inferior (the result, i.e.), just that a table saw is *designed* for ripping. When ripping with a RAS, you have to contend with the saw itself being in the way. Additionally, the blade motion wants to lift the work (same with dados) so one has to be alert. Someone mentioned that they lack splitters but I've never seen one that doesn't have a splitter and pawls to grab any kickback.
-- dadiOH ____________________________
dadiOH's dandies v3.06... ...a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico
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dadiOH (in eXkTf.2718$I7.2200@trnddc03) said:
| Someone mentioned that they lack | splitters but I've never seen one that doesn't have a splitter and | pawls to grab any kickback.
I've never seen a RAS with a splitter (you can get a look at mine in the top two photos at http://www.iedu.com/DeSoto/RAS_Table.html ). The anti-kickback pawls _are_ pretty much standard; but it's a whole lot better to prevent kickback in the first place. I do _all_ my ripping on the TS - and nearly always with all three of splitter, hold-down rollers, and featherboard.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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wrote:

Since most kickback involves the rear of the blade lifting the board, would the basic design of a RAS mellow it? The "kickback" would actually be forced down into the table.
Barry
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Ba r r y (in snipped-for-privacy@4ax.com) said:
| Since most kickback involves the rear of the blade lifting the | board, would the basic design of a RAS mellow it? The "kickback" | would actually be forced down into the table.
I don't know. When I first got the RAS (early 70's) I shot a 1x6x96 about 30'. It didn't have a pronounced downward vector, nor did it seem mellowed in any way.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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wrote:

Now that I think of it, it would trap the board, just like routing with the board between the bit and the fence.
Ouch! <G>
Barry
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Ba r r y (in snipped-for-privacy@4ax.com) said:
| On Sun, 19 Mar 2006 17:59:19 -0600, "Morris Dovey"
| | || || I don't know. When I first got the RAS (early 70's) I shot a 1x6x96 || about 30'. It didn't have a pronounced downward vector, nor did it || seem mellowed in any way. | | Now that I think of it, it would trap the board, just like routing | with the board between the bit and the fence. | | Ouch! <G>
There wasn't any 'ouch' - at least not a human one. The good news is that was also my _last_ incidence of RAS kickback. Since then I've used that machine to rip, mold, and rebate thousands of feet without a second 'event' - and I'm inclined to chalk that one up to ignorance, over-confidence, and failing to set the anti-kickback pawls properly. It wasn't long after that I made my first featherboard and hold-down fixture for ripping.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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For what its worth, a few years back I had to rip a few hundred bd ft of wood to very narrow widths. less the 1/2 inch. I set up the RAS to rip the boards with the back of the blade slightly canted toward the fence and a splitting pawl set up about 18" back of the blade. After each cut the narrow strip would fly out of the saw fly through the shop door and land about 20 ft out in the yard. They all landed in a "fairly" neat pile and the kick back was never near me. It was a lot easier then using a push stick to clear the saw blade with each cut and seemed to work quite well. It is the only time I have ever tried to get a saw to intently kick back
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said:

I had a Craftsman TAS and the splitter was a small plastic wheel that was located between the kick back paws.
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I have owned several RAS during the last 4 decades. I gave my last RAS to my son. There is a mechanical (law of physics) problem with a column mounted RAS. It is know as the "Right Hand Rule". Simply put, if you curl your fingers in the direction of the spin of the motor, your thumb points to the direction of a significant undesirable force that is being applied to the motor and blade. Additionally, the further from the column the force is applied, the greater the longitudinal pressure is directed to the arm and saw.
Basically, this force is trying very hard to force the arm away from a true 90 degree track. It is also magnified when dadoing in a crosscut mode. Again, the greater the depth of cut, the greater the resulting force on the arm and the greater the possible inaccuracy. The Delta 12" RAS is constructed differently. Notice that it is suspended on a track that is centered on the main arm. Theoretically, the error is "averaged out" over the travel.
I have learned to minimize the errors to a tolerable degree but I've never been able to guarantee myself a truly "square" set of cuts over a large area.
I still miss my old RAS.
John
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Well, that explains why my router table keeps levitating!
You are kidding right? My full width cuts are dead square.
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wrote:
[top posted for your convenience]
I believe you've seriously misapplied the "Right Hand Rule". For those wondering, it's what describes the operation of gyroscopes. The analogy between gyroscopes and radial arm saws that might permit the application of the RHR fails when you consider that a gyroscope will tend to right itself in accordance with the RHR when a force is applied parallel to its axis and perpendicular to the plane of the rotating mass (let's call it a disc for this discussion).
However, all the forces applied in the motion of the carriage of a radial arm saw are perpendicular to the axis and in the plane of the disc. In order to apply the analog of the gyroscope, you would have to apply a force to the edge of the saw blade (disc) perpendicular to the disc, which would be a very dangerous thing to attempt and would trump all other calamaties attributed to the RAS.
You can turn a gyroscope all day long in the same axis in which the disc is spinning and no precession will occur. It's the same with the radial arm saw.

--
LRod

Master Woodbutcher and seasoned termite
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The particle board table top is not as smooth as cast iron. Other than that, nothing.

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Joseph Handy wrote:

Joseph,
Concerning the posts you're seeing on ripping, I have to disagree. Ripping works great on a RAS -if- you use a sled. A sled is simply a flat piece of material, usually larger than the working piece. A big piece of MDF works great. By firmly clamping the work piece onto the sled, it's nearly impossible to get the work piece to bind. And even if it does, you're nowhere near where the material will be sent flying. Plus, your fingers have no reason at all to even approach the spinning blade.
When I use a sled to rip, the cuts are straight enough to glue together without jointing. I can send you pics if you like.
The only down side is the weight and bulkiness. So for really big pieces, you're gonna need table extensions or rollers. But the same would hold true for a table saw. And, for really big pieces, it'd be true without the sled.
--
Michael White "To protect people from the effects of folly is to
fill the world with fools." -Herbert Spencer
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