Table Saw Molding Head

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Still I would much rather be hit by that cutter then the 30-06 bullet .
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The thing is you might not have control over some nut with an 06 but you do have control over what kind of tool you buy or how you use it.

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Huh?
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Well you have probably 400 grain for the cutter. Its not brass and lead like the bullet so it is going to be larger on the size to weight ratio. Then a 200 grain bullet is probably going to be coming out of a more powerful gun with a muzzle velocity of about 15 to 20 times more speed than the molding head cutter.
What do you think? The object is 2 or 3 times heavier but 15 to 20 time slower speed.
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Don't you think he'd notice if there was a cutter missing?
In fact, there is such a thing as a one-cutter head. Sears used to sell one, but it seems they don't any more. It's not perfectly circular; there are strategically-placed flat spots to keep it balanced.
Somebody sold one on eBay recently: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item 0086210874 Pic shows both 1-blade and 3-blade Sears molding heads.
FWIW... I've never heard of a 2-cutter molding head. All I've ever seen is 1- and 3-cutter heads.
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Craftsman had the 1 cutter version also. The cutter head that that cutter fits into is not perfectly round and compensates of the single cutter.
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Having done a lot of moulding work over the years I would not touch a single cutter cutter head on that type of setup. I would sit down and scrape the mould by hand using no more than a blunt butter knife rather than use it. It is possible that the head may be balanced with a counterweight opposite the knife. The only problem with this theory is how do you compensate for different size/shape/projection/weight knives? I can not imagine how but maybe the head is designed with a depth limiter to limit feed rates. If it is not you are talking a major risk of kickback at that diameter and speed.
Although not a recomended practice but an accepted practice is to use different shaped cutters on the same head at times on spindals (shapers). Occasionally for a one of run you might only grind 1 knife and just use a blank on the opposite side. Whenever I do this I always have a rubber lined 1/4" plate guard between me and the cutters. The rubber is to catch the chips of the end of the cutter when it hits the guard. Even the ammount of knife projection has a marked effect on the inbalance.On a spindle we are only talking about a 3" head running on very heavy bearings and shaft compared to the 8" you are talking on a TS on relativly light bearings and smaller shaft. A spindle running collars runs at around 4000rpm, 4500 is the maximum recomended for that type of cutter. That gives a spindle cutter a surface speed of 4,188'/Min (4,712'/Min at max) allowing 1/2" projection for cutter. Assuming 8" moulding head on TS you are looking at 7,200'/Min.surface speed with no cutter projection. On a spindle even if the knives are roughly the same size the ammount of vibration due to the inbalance is incredible. And needless to say the risk of throwing a knife and kickback increases dramaticly as well as lower quality finish. I used to have the formula for working out the inbalance taking centrifigal force into account but forget it now. Maybe someone else in here can shed dome light on that subject. I know I for one would be interested in knowing it again.
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After doing that for several days on end, you might reconsider using the single cutter design. LOL If you have never seen one in operation, don't knock it.

knife.
Tthe counter ballance is more likely engenereed to be dynamically balanced like car tires are balanced. Counter balance weights are spread over an averaged out area in multiple spots so that minor variations are not so significant. Typical wheel weights on automobiles are placed in as many as 4 locations to off set the heavy spot when tires are staticly palanced. If a single weight is thrown off the unbalanced effect is much less dramatic than if a single weight is thrown off opposite the heavy spot.
The only problem with this theory is how do you compensate for

Size and shape will not have any effect on balance if the cutter unit is balanced. Balance on a spinning object concerns weight, not shape or size. I strontly suspect that different shaped cutters made ofr a single head cutter will be shorter or longer so that different profiles each has equal mass regardless of shape. You would not want to run the cutter head with out a cutter in it or a 3 cutter head with only 1 or 2 cutters in it.

This would be a totally different situation and while it may be accepted, that is truely throwing the cutter head out of balance by introducing different weights in other locations.

Again, if the single cutter is balanced the load on the bearings is a non issue.
A spindle running collars runs at around 4000rpm, 4500 is

Again, a single cutter head cutter will be balanced so vibration will not be as great as you make it out to be. A cutter does not have to be perfecetly symetrical to be balanced.
And needless to say the risk of throwing a knife

While I'll bite at the possiblilty of a kick back providing your feed rate is "much faster" than recomended , the increase chance of throwing a knife is non existant when copmpared to a 3, 12 , or 90 tooth cutter. Think about single flute router bits that spin at 25,000 rpm. It's all about balance when it comes to spinning irregular shaped objects.
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Doubt it I have lots of patients and besides if its achoice between somthing taking a long time or having the hands to do it with, the hands wins hands down

Its asicly the same as set of collars with one knife and one blank except larger.

The only practical option i see here that might wirk to allow for differing weights/projections would be a fluid filled head working on the same principle as an. automatic transmition torque converter,You must also remember that increasing projection also upsets balance.

I strongly disagree here. Change the weight or the amount of projection and you affect balance considerably. For a spinning object to balance it must be balanced at that particular configeration. Change that configeration and you upset the balance.

Even at equal mass if one cutter projects further than another it will affect balance.

So is changing the one cutter in a single cutter head

that is true IF a single cutter is balanced.

Unless it has some form of dynamic balancing that will 'adjust' itself on the run it will not balance with varying knives

No it does not. I have some knives which are different but designed to run as a pair. But the design of knives in this situation takes considerable design considerations taking into account weight distribution in relation to projection to compensate for varying shapes and centrifigal force.

Sorry I do not follow your point there. The increased risk of throwing a knife is due to the inbalance, nothing to do with the number of knives

Thats right ... weight is distributed equally in any direction from centre, bit is balanced although oposing sides are different. Now lets take that same router bit and grind or break half the carbide tip of ( simulating changing cutter shape) ...... woops what happened to that perfectly balanced bit.

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No, I would say that the cutter head is weighted to compensate for the weight of a cutter and all cutters for that head are of the same weight.

Increasing projection will up set balance if the changing projection remains the same weight.

Correct if the projection changes after the balance has been made. Differnt projections would have to be made heavier or lighter to compensate for their changes.

Correct. That is why the cutter with another projection would have to be made lighter or heavier to maintain the blaance. Add or take away length.

Ok, you are assuming that all cutters for the single cutter head are not tuned for that particular cutter head.

This cutter head that we are discussing has been around for a long time. There have been no complaints of there being a vibration or balance problem that I have ever heard of. This is not all theory, the tools exist and run with out exagerated vibration.

We are both beating our heads against a brick wall here. ;~)
The tool exists and has for many years. Apparently it works.
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