Table Saw Molding Head

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Hi,
I never have any experience with Table Saw Molding Head, maybe the experts in this forum could give their opinion.
I saw a tabl saw molding head with one blade. Is it good? Would it worth buying? How does it compare to the typical 3 blade head?
Thanks in advance for any opinion given.
Best Regards, Jo
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Jo wrote:
> > I saw a tabl saw molding head with one blade. Is it good? Would it worth > buying? How does it compare to the typical 3 blade head?
SFWIW, I threw my Craftsman set, unused, in the trash years ago.
Lew
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Har! I never used the set I bought 30 years ago. I'm sure it's around here somewhere, but damned if I know where.
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What brand? I saw a sewing machine that was electric, is it good?
A 3 cutter head will last longer.
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Craftsman.
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Not the best brand but it will do the job. Be very careful, use guards, and feed very slowly with hold down and push sticks. Wear eye protection and preferabley a face mask.

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Before I had a properly tooled shaper I used a three knife molding cutterhead quite a bit with a great deal of success. never used , nor even have seen, a single knife cutter.
The downside to molding cutterhead is low surface speed, I would say, and because of it , controlling tearout is much more difficult. You can get acceptable results, however if you are careful about backing your cut and use slow feed rates. At least that was my experience.
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Personally, I have never heard of a one-blade moulding head. I have had a three-blade cutter for 30 years. It used to get a fair amount of use but bigger, better routers and router bits seem to be replacing it,
The three-blader can do a fairly good job if you feed slowly. Remember that most routers are running in the 18,000 to 22,000 rpm range. A shaper (which the moulding head is trying to simulate) also runs quite a bit faster than your table saw, which is in the 3,000-4,000 rpm range. If you start shallow, and work up to final cutting depth, and feed slowly then can do the job - but not as well as the router or shaper. I would approach a one head cutter with a fair amount of caution.
RonB

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It is absolutely necessary that the molding head is balanced when it is running. I've never heard of a one cutter molding head, so I suspect that it's a 2 cutter molding head with one cutter missing. DON'T USE IT, until you are absolutely sure that it's got all of the knives in place that it's supposed to, and make absolutely sure that all of the knives are properly secured in place before you even put it on your saw. Even then, always stand well out of line of it when you turn the saw on, as these molding heads have been known to throw a knife occasionally.
I have had a 3 knife Craftsman for over 30 years and I have used it quite a few times, but less and less as I get older and less brave. I've always felt very un-safe whenever I have used it, even after taking extra time to be sure that all of the feather boards and necessary guards were in place. I feel much safer doing the job with a router or shaper. These table saw molding heads can get the job done, but they run much slower, cause more chip-out, and are much less safe then doing the same job with a router or a shaper. I have had pieces of molding completely shatter when cutting them with one of these, sending large splinters all over the shop. They definitely aren't for the timid or un-skilled user. I haven't trashed mine yet, because every once in a while I still find a need for it, but I avoid using it whenever possible.
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Charley


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No, they do make them. Presumably they are balanced more or less properly. But 3 cutter heads are dangerous enough; using a 1 cutter would be crazy.
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Could you explain how 1 cutter would be crazy?
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Leon, wrote the following at or about 3/27/2007 3:46 PM:

Not sure that it would necessarily be crazy but I think it might be a bit more prone to get a bit too much material in there, a bit too quickly and watch it (hopefully that's all) go flying.
Three bits, means you're removing the material 3x faster. This makes for a smoother finish. It also means that at a given feed rate it will remove 3x the material. Just seems that it would be more likely, with one cutter, to be able to feed a bit much in and wind up with a big ker-chunk and a load of splinters flying or the whole damn thing taking off on you.
I've had the 3 head unit from Craftsman for about 35 years and recall that they sold the single head at that time as well. The three head cutter (on a RAS, no less) and set up with proper guards, fencing, feather boards, etc. is pretty scary.
It does a nice job if you take your time on setup and feed slow. One thing you won't like get is complacency when using that puppy. It seems to provide its own wake-up call every time you power up<g>
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I have had the 3 head set for almost that long. LOL Since 1978 IIRC.

I agree with probably a smoother finish but at a given feed rate, the material removal would be the same on either the 1 or 3 cutter design. The single cutter would actually be removing more material at that given feed rate.
Just seems that it would be more likely, with

Perhaps so but with the cutter tip speed being approximately 50 MPH (73' per "second") and your feed speed being say 5' per "minute", a double feed rate of 10' per "minute", the ratio of feed to spin speed is still quite steep. I think the feed rate would have to be much higher, 100 peet per minute before the 1 cutter design would be more likely to take a huge bite than the 3 cutter design.

Yeah I had this set up on a RAS also.

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THe single cutter at a continuous feed rate would remove the same ammount ......BUT ... the 3 cutter removes it in 3 smaller chips as opposed to one large one giving much better quality finish.

At any given feed rate the single cutter is taking a larger bite.

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What I was trying to get at was that the single cutter removes more "per cutter" than the 3 cutter design at any given rate.

Which I do not dispute, given the cutter speed vs. feed rates the single cutter does remove more per revolution but certainly not 3 times "dangerous capacity". Regardless of which configuration is being used the cutters are not removing a large quantity of wood. The feed rate would have to be close to the speed of the cutter head, "50 mph" for the 3 to 1 capacity ratio to come into effect. More likely for each revolution and the typical feed rate, each triple cutter probably removes 1 or 2% of its capacity and the single probably removes 3 to 6% of its capacity. I believe feed rate would have to be drastically increased before a significant increase in danger would be noticed between the 3 and single cutter head design. By comparison, a 30 tooth blade is not much more likely to cause a tragic problem than a 90 tooth blade.
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Leon, I think we are misinterperating each other somewhere.To hopefully make things clearer we will exagerate things a bit. Material is being fed at a constant rate. Keyword being constant, Regardless of that being 5" per hour or 50mph. Lets say that the stock moves into the cutter 3/16" and the cutter has done one revolotion. The 3 knife cutter has removed 3 X 1/16" chips through this 1 revolution. The single knife has removed 1 X 3/16" chip. The same amount of material is removed in either case. It is just the size of the chip(s) that has varied.

Regardless of the feed rate you still have one head cutting one chip per revolution compared to the other cutting 3 small chips per revilution. You can feed a 1000mph if you like the number of cuts per revolution does not change. The one knife head will still cut one and the 3 knife head will still cut 3 per revolution.

I'm sorry, maybe I am spinning in reverse, but i don't follow what you are trying to say here. Per revolution each cutter should remove 100% of its capacity. Three knife will revove 33.3% per cutter and the single tooth 100%. Either way you still get 100% cut. My previous 2 comments explain this.

Any increase in feedrate always generates larger cut regardless of number of knives an thus increases risk of kickback. Refer previous comments on chip size

Thats like comparing a triangular or square wheel to a round wheel.There is a major difference between 1 tooth going chunk, chunk, chunk compared to to a 30 or 90 tooth saw blade running smoothly through a revolution.(once again chip size) A 30 tooth blade is slightly more likely to cause kick back than a 90 but it is a very very marginal ammount.
I hope that clears things up little. In summary Slower feed rate regardless of number of cutters means smaller chip size which in turn means better finish and less danger. Higher feedrate means larger chip size which means poorer finish and greater danger. More cutters at specific feedrate means smaller chip size which means better quality finish and less danger of kickback.
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SNIP.
LOL... I think we are probably on the same page here Paul. I am only trying to make the point that while a 3 cutter vs. a 1 cutter head probably makes a smoother cut, with a given constant recommended feed rate cutters on both units are most likely well within their capacity of making a safe cut. While your example of the amount removed ratio is correct, I suspect that the amount removed by either stile cutter head at operating rpm is in the low thousands of an inch per cutter pass. If the 3 cutter head is removing 10 thousandths per cutter the single cutter is removing 30 thousandths.
That said, LOL, the single cutter is probably more likely to give a crisp clean cut than a 3 head cutter providing your feed rate is 1/3 that of the 3 cutter version. I have the 3 head version and the cutters do not perfectly fit in alignment with each other. When I use the beading bit the resulting bead is not as perfectly formed as the profile on any single cutter. Because they do not register in perfect alignment on the head they each cut at a slightly different location resulting in a profile that is not exactly like any one cutter.
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I did say I was exagerating a bit. 3/16 was just a nice convenient figure to work with. Maybe i shoul have went to 3/8 LOL

I theory the single knife cutter head at 1/3 the feed rate should give exactly the same quality of finish. I dont know about you but I am not getting any younger and might not have enough time left to take 3 times as long to do the same job

Any multi knife cutter suffers from the same problem. It is the combination of the shape of the 2 or 3 knives whatever the case might be that determins the final outcome. When hand grinding knives like I do it takes quite a considerable number of years practice before you can grind a near perfect set of knives so that they all do their fair share of work and are balanced. Note I said near perfect. Although it is possible to make a perfectly matched pair of knives freehand the time involved far outweighs the benefits. I did do it once for a very special set of knives but you wouldn't want to be paying me for the hours spent stoning / checking/ stoning / checking .... and it goes on. At times this 'feature' is actually useful. Lets say I am grinding a set of knives for a particular moulding to match clients house and I accidently go a little deep in one spot .... woops ... not to worry I just have to make sure that that particular spot on the other knife is correct.
Just as a side point for anyone interested, grinding a set of knives to match a particular moulding is not as simple as 'tracing' the shape onto the cutter and grinding away. The shape has to be projected to take into account the rake angle of the particular head you are using and the projection of the knives. Set up those knives in the same head a second time but project them out a little more or pull them back a bit and you will get a slightly different shape on the moulding. Put those knives into another head with a different rake angle and once again you get a slightly different shape moulding. The difference is not that noticable to look at but don'y try to mitre or butt join the two pieces together ... it will make you look like a poor woodworker.
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You know, I never really noticed whether the grind was identical on the 3 knife cutters that I have. I did notice however that none of the cutters would seat in the same position on the cutter head. Tightening the set screw would often nudge the cutter a bit. And now you throw in the fact that cuter knives are not always perfect. LOL
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You both have stated it somewhat differently but you both were saying the same thing. All else being equal, the chip load on the single flute cutter is greater.

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