Thread: Can you get half core router bits with 1/4" shanks ?

Hi Jake, The largest I have seen in core box bits with a 1/4" shank is 1".

Regards
Harold

thanks Pal,

1" would be fine too. As long as its the half core type with that larger radius.

I think your problem will be that 1/4" shank bits are more subject to virbration/wobble than 1/2" bits, so very few companies are prepared to make bits much over 1" in diameter, regardless of the radius required.

I seem to remember that Carbitool in Victoria will grind custom bit shapes, so a call to them may be in order. I think you are looking for something vaguely mushroom shaped, with as big a cutter diameter as possible, but with the major radius of the cutting head being in the 2" to 3" range - sort of like a panel raising bit without the bearing/pilot fitting in the middle. But a custom bit won't be cheap.

Does it have to be able to plunge in? If not you could get a cheap-ish panel raising bit & have the pilot ground down.

Originally Posted by bsrlee

Does it have to be able to plunge in? If not you could get a cheap-ish panel raising bit & have the pilot ground down.

Like it ! ........thankyou. seeing how that could work. But now wondering if panel raising bits come with 1/4" shanks ?......( imagine they do else you wouldn't have mentioned )

I'll have a bit of a ebay search amongst the hongkong specials and see what I come up with.

thanks mate

I have the urge to scream DON'T EVEN THINK ABOUT IT!!

I have had a trimmer throw a slot cutter bit across the factory, fortunately no-one was in the way but it scared the cr@p out of me. When I found it the whole shank was bent about 30 degrees.

A panel raising bit would be even bigger and heavier so even the slightest imbalance in the bit at 30,000 rpm will not end well.

Aside from that, the average 400W trimmer probably won't even be able to push a bit that large.

But if you do go ahead with it I'd recommend a full suit of steel body armour just in case.

Originally Posted by elanjacobs

I have the urge to scream DON'T EVEN THINK ABOUT IT!!

I have had a trimmer throw a slot cutter bit across the factory, fortunately no-one was in the way but it scared the cr@p out of me. When I found it the whole shank was bent about 30 degrees.

what were you doing to the poor thing that caused it to spit the dumby ?

A panel raising bit would be even bigger and heavier so even the slightest imbalance in the bit at 30,000 rpm will not end well.

I wouldn't use it if it was imbalanced.

Aside from that, the average 400W trimmer probably won't even be able to push a bit that large.

I would say success or not would depend on many factors. Do you know how I intend to use it

But if you do go ahead with it I'd recommend a full suit of steel body armour just in case.

I haven't got that but I've got a cricket box. Should be enough to cover my last remain ball.

I had a wheel come off my car once at 60. Scared the crap out of me too. I dare not drive any 3 wheeled cars anymore over 70, unless jesus blesses me the day before with a candy cane.

In order:

Wasn't doing anything unusual, just cutting a 15x3mm slot in MDF.

Unless you have a dynamic balancer, it is highly unlikely that you'd be able to detect a problem.
As an example:
An imbalance of 0.1 gram at the edge of a bit that's 60mm across and spinning at 30,000 rpm will put 3kg of sideways force on the spindle.
See here for the relevant calculation: CalcTool: Centrifugal force calculator

It is true that I don't know what you intend to use it for, but based on the force alone I can't advise against it strongly enough.

Originally Posted by elanjacobs

In order:

Wasn't doing anything unusual, just cutting a 15x3mm slot in MDF.

Unless you have a dynamic balancer, it is highly unlikely that you'd be able to detect a problem.
As an example:
An imbalance of 0.1 gram at the edge of a bit that's 60mm across and spinning at 30,000 rpm will put 3kg of sideways force on the spindle.
See here for the relevant calculation: CalcTool: Centrifugal force calculator

It is true that I don't know what you intend to use it for, but based on the force alone I can't advise against it strongly enough.

the problem as I see it is. And its a typical problem I have with most analysis (not that I'm saying I'm better ) .......is those issues you just brought up are generalised. Incomplete. some would even be irrivelent(spelling ?). And I feel I can safely say that all because.........

you don't know how I'm going to use it . I haven't even discussed things like....timber types. cutting direction wrt grain, cutting passes (at what depth each pass?) . amount of blade thats actually going to be cutting (I may half of the blade buried in some kind of reference fence I've got planned) .

If you can come up with accurate danger odds on what I'm to do with it ,then ,I'm all ears and will jump on the alarmist bandwagon ok.

Anyway, can't find any hong kong specials on ebay. Got any old panel raising bits with 1/4" shanks I could buy from you ?

Don't have any panel raising bits at all, only spindle moulder knives.

As for grain direction, pass depth, etc. I wouldn't even trust a bit that size spinning freely with no load at all.

That's all for my rant, I can only give my opinion based on experience and a Cert III in wood machining - I can't make you not do it

Originally Posted by elanjacobs

As for grain direction, pass depth, etc. I wouldn't even trust a bit that size spinning freely with no load at all.

you must be kidding.

That's all for my rant, I can only give my opinion based on experience and a Cert III in wood machining - I can't make you not do it

all good . I understand you have to follow something even if they don't present you with odds.Goodluck with whatever you follow (just please don't believe everything your told)

apricotripper, If you intend to put a 60 or 70 mm diam cutter in a trimmer, make sure you have insurance, or you new name will be bodyripper .
As you see by my age I've been about for a few years, 60 of those in joinery and cabinet making. Don't do it regards John.

I have been following this thread for a while but have refrained from commenting so far.

I am pitching in now to add my voice to those who are advising against using the large bits in a trimmer.

The fact that you have difficulty finding these bits with a 1/4 inch shank in itself should tell you something.

Doug

all right then. I'll stop it here.

Deja vu for me because I've been down a similar road on this site over a router bit, where I was told I was a fool impetueously. Ended up showing that I wasn't wrong afterall. That process I came up with is used now in every chair I make, and feels as safe as houses, and will continue using, yet the bit would used be considered far worse than what I want to discuss here. so whats the point continuing here which will lead to all sorts of kneejerk rubbish assumptions (especially from noisey locals who it has nothing to do with, who want to talk people, and feel secure in siding friends as though its some kind of hobby), despite the strong possiblity (in my mind) that such a discussion will lead to a sweet process to speed up stock removal of a particular rocker part.

I have respect for those who have experience. Its unfortunate I have to look ignorant of it however, to follow my instincts on something I feel certain about.

Just thrilled I work for myself now, where I can do what I like. No more forcing myself to zip my mouth for months on end to avoid debates with egomanics and their assumptions.

Have a merry christmas.

Originally Posted by apricotripper

hi,

basically what the titles says. with a radius 45 or 75mm would be fine.

I want one to fit my trimmer, and the only ones I've found have 1/2" shanks.

Willing to buy second hand if you've got one you want to offload it.

thanks

Jake

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