power router problems

[thetyreman]

I was routing a slot for a guitar, luckily it's just a prototype test piece, but it came out wider than it should be, the bit is 1/4" but the slot measures around 10mm? what could be causing this? I'm a power tool noob.

 

[niall Y]

I've had this with small cutters especially single flute ones - the slot becomes wider than the cutter. This is going to happen to an extent anyway, as the cut is dynamic and any eccentricity will be magnified. A good quality cutter will give a better result,
If the swarf isn't clearing properly this could also be having an effect on the width. Also if you are making several passes and the fence isn't completely rigid. From 1/4" to 10mm ( nearly 4mm) does seem a lot.

 

[thetyreman]

hi, it's a really good bit, wealden tools, I'm thinking it must be the collet, it doesn't go in very far into the collet.

 

[Spectric]

What router are you using ?

 

[niall Y]

Hi there - Yes I would make sure the collet is clean and properly tightened. If no joy , you could go down a bit size and try a 5mm or even 4mm to see if this will give the result required. Might be worth checking with some of your other straight bits to see how accurate these are, which might give an indication as to where the fault lies. Wealden are a fairly good supplier of bits, but something like Titman cutter might be more accurate.

Edit, Might be worth checking if your collet is 6mm rather than 1/4" which might be affecting the performance.

 

[recipio]

You seem to have a lot of the shank exposed. Try and bed the bit down to the base of the collet and then retract just a few mm. Take a few passes if the groove is any deeper than a 3 - 4 mm.

 

[thetyreman]

What router are you using ?

it's an old bosch GOF 900 ACE

 

[thetyreman]

You seem to have a lot of the shank exposed. Try and bed the bit down to the base of the collet and then retract just a few mm. Take a few passes if the groove is any deeper than a 3 - 4 mm.

it won't go all the way to the bottom of the collet even if I try, also don't want to force it, I take it this means the collet is the wrong size?

 

[thetyreman]

some measurements.

 

[recipio]

The problem seems to be that the bit is describing an eccentric circle due to a poor fit in the collet. This is dangerous - it could easily throw the bit at high speed. The spiral bit is obviously 1/4 inch shank. I wonder if you have a 6 mm collet installed by mistake. ? You are measuring the locking nut - try and prise the actual collet out and measure again. After a clean and a little WD40 the bit should slide easily in the collet but make sure it's a 1/4 inch. ! You should be able to rout a perfect 1/4 inch groove with the technique you use but it takes concentration.

 

[HamsterJam]

majority (at least 3/4?) of the shank should be secured in the collet.

 

[worn thumbs]

The problem seems to be that the bit is describing an eccentric circle due to a poor fit in the collet. This is dangerous - it could easily throw the bit at high speed. The spiral bit is obviously 1/4 inch shank. I wonder if you have a 6 mm collet installed by mistake. ? You are measuring the locking nut - try and prise the actual collet out and measure again. After a clean and a little WD40 the bit should slide easily in the collet but make sure it's a 1/4 inch. ! You should be able to rout a perfect 1/4 inch groove with the technique you use but it takes concentration.

My thoughts also.To be sure,can you pop the collet out of the collet nut and see if the tool shank easily passes through the collet?You ought to have around +/- 90% of the shank engaged.If,as seems likely,it doesn't then you need a bigger collet and I would have thought they are easily sourced if you have a Bosch part number or perhaps you need to scour ads for those which claim to be a suitable type.A 1/4" collet will normally close enough to grip a 6mm shank but the reverse isn't the case.The other possibility-and I don't know the machine-is that the collet isn't retained properly.some machines have a snap ring that fits a recess in the collet and if it isn't properly located the tip of the tool can be rotating a bit away from the axis of the machine.

 

[Phil Pascoe]

I assume you cut this in one pass?

 

[clogs]

if I understand this correctly.....?
to do that in one cut/pass in steel costs thousands
to get the same accuracy with one cut in wood will also mean a lot of money.....
best is to cut a slot of a smaller width than the requirements then expand it to ur req size.....
the altering softeness in the wood *knots n grain direction* plus a flexible means of a guide/hand held router regardless how tight u clamp it wont help.....
and of course there's all the dust n chips getting in the way.......even with a spiral bit....which is harder to control by hand anyway....
also what depth....?

I can get chatter and in accuracy doing just that on my Bridgeport mill and that weighs a ton....

what do u expect with hand held equipment....

u can see why CNC has taken over in the accuracy stakes....
I think ur asking to much with the equipment u have.....sorry...

 

[Phil Pascoe]

There is no reason whatsoever why he shouldn't get a perfectly accurate cut with a router.

 

[J-G]

A 1/4" collet will normally close enough to grip a 6mm shank

Not in a million years! - An 'ER' Collet has a 'potential' range of 1 mm in most sizes (0.5mm in some) but the type of collet used in routers - with just 3 or 4 slots cut in one end - will only securely clamp a range of a few thou, 5 would be asking a lot, I doubt that a 6.25mm shank would ever clamp in a ¼" collet, never mind a 6.0mm one.

 

[thetyreman]

I assume you cut this in one pass?

yes

 

[Phil Pascoe]

and the slot's width was uniform over its length?

 

[worn thumbs]

Not in a million years! - An 'ER' Collet has a 'potential' range of 1 mm in most sizes (0.5mm in some) but the type of collet used in routers - with just 3 or 4 slots cut in one end - will only securely clamp a range of a few thou, 5 would be asking a lot, I doubt that a 6.25mm shank would ever clamp in a ¼" collet, never mind a 6.0mm one.

Well, all I can say is that I have one that works with both.

 

[Yojevol]

I can see from pic no.2 that the cutter is kicked over to the right. I would say it's lack of engagement in the collet.
Brian