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.
Posted via a free Usenet account from http://www.teranews.com
> I saw a tabl saw molding head with one blade. Is it good? Would it
> buying? How does it compare to the typical 3 blade head?
SFWIW, I threw my Craftsman set, unused, in the trash years ago.
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.
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.
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.
"RonB" < firstname.lastname@example.org> wrote in message
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>
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
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.
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.
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
Any increase in feedrate always generates larger cut regardless of number of
knives an thus increases risk of kickback. Refer previous comments on chip
That I agree with, but here you are talking a totally different cenario.
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.
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
More cutters at specific feedrate means smaller chip size which means better
quality finish and less danger of kickback.
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
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
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
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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