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Why am I making bananas with my tools?

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mickthetree

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I'm sure I've heard tale of this before, but I seem to be making bananas with two of my machines. Namely my jointer planer and my mitre saw.

I have set the fence on my Axminster jointer to 45 degrees and I am trying to plane the edge of a piece of ply to exactly 45 degrees for my donkeys ear shooting board attachement. I dont normally have any problems with planing stock flat and square at 90 degrees. However, the edge is looking more and more convex the more I plane it. What am I doing wrong?

I am also trying to cut some mitres on my compound mitre saw (Metabo KGS255). Again, no probs at 90 degrees and so slop in the saw so should give good results at 45 degrees as well. However, whether I use the saw beveled at 45 degrees or angeled to 45 degrees I seem to creating edges far from square. The edges are curved. I'll try to take some photos.

Confused and frustrated of Tring.
 

CHJ

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How positive is your stock location against your fences ?

Also on your mitre saw have you checked the squareness of your blade spindle to all axis, a blade can be out of true and still cut a reasonable 90 deg. but error can be magnified as soon as you attempt a bevel.
 

mickthetree

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Hi Chas, the blade of the saw shows as 90 degrees to the fence and bed when cutting a 90 degree angle. Is this what you mean?

I've tried holding the wood more firmly against the fence of the jointer. I am taking very light passes so I might try a heavier cut and see what happens. Doenst amtter if I remove more wood.

Cheers
 

CHJ

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Basically yes to the mitre saw, but the fact you are getting an error when the blade is not at 90 deg. to the fence/table smacks to me as though you may be getting a surface formed by the blade periphery curve as though something is not in line with your direction of cut.
 

andersonec

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When the blade is going through the wood at an angle, the wood tends to get pulled backwards in the direction of the cut, only fractions but enough to make a curve. When cutting mitres, make sure you use the screw-down clamps which are usually fitted within the fence, holding it with your hand against the fence will not be enough if it is a wide board.

When making planing cuts at 45deg. make sure that as soon as the wood touches the outfeed table that it is referenced against the outfeed table at all times and ignore the infeed table, so, it is held against the fence and the outfeed table.

Make sure your blade guard is covering the block and almost touching your wood.

Andy
 

disco_monkey79

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Can't help with your query, but at least you can take comfort from living in Tring. We visited the Nat. History museum there the other week - the town is lovely.

Hope you get it sorted soon.
 

woodbloke

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mickthetree":1d2x20yq said:
I'm sure I've heard tale of this before, but I seem to be making bananas with two of my machines. Namely my jointer planer and my mitre saw.

I have set the fence on my Axminster jointer to 45 degrees and I am trying to plane the edge of a piece of ply to exactly 45 degrees for my donkeys ear shooting board attachement. I dont normally have any problems with planing stock flat and square at 90 degrees. However, the edge is looking more and more convex the more I plane it. What am I doing wrong?
It's probably too late by now, but ply is the last thing you should be putting across the blades of a p/t...I suggest you check the condition of the blades for dings and lumps missing. With any luck you'll have got away with it [-o< ...I didn't :( - Rob
 

Dodge

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Regarding the problems you are experiencing there are two things that I would be inclined to suggest but without seeing the machines may be off the mark.

Firstly with your mitre saw, whilst Metabo are a good make when was the blade last serviced/sharpened and is it a good quality blade - I have seen some attrocious cuts made by poor quality or dull blades.

With your surfacer I would imagine that it is the setting of your knives to the outfeed table is out causing your timber to come off it less than straight. I would check and adjust the blades first and take it from there.

Rog
 

mickthetree

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The blades seem fine after their confruntation with the ply. :) They are probably due a sharpen anyway, but they still give perfectly acceptable results. As the timber comes out square and true at 90 degrees I'm pretty happy with the surfacer /jointer / planer's setup. It seems like I may have been putting downward pressure on the infeed table as keeping all my pressure as Andy said on the outfeed table seems to have worked much better.

I always do this when working on flat and square stock. I think using the planer in this new way I must have not considered this.

The mitre saw is still pretty new. I've not used it very much and the blade was one of the better ones these saws came with. I'm sure a mitre saw isn't the right tool for cutting fine mitres for boxes, but its all I have and I wanted to trry it.

After much fettling and farting about I now have a much much more accurate donkeys ear attachment for my shooting board. I'll be making a new more accurate version (as well as a new shooting board) with what I have learnt today, but I have a nice very nearly 90 degree mitre gluing up in the shed as we speak :) :)

I am trying to setup some methods for creating boxes faster than I currently do and a good shooting board for my situation will definately be a great boon.

Thanks guys
 

CHJ

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mickthetree":2skxzrx0 said:
.....The mitre saw is still pretty new. I've not used it very much and the blade was one of the better ones these saws came with. I'm sure a mitre saw isn't the right tool for cutting fine mitres for boxes, but its all I have and I wanted to try it.....
There is no reason a mitre saw should not produce accurate mitre angles, mine is a budget end Rexon with a decent blade fitted and it nails my segment angles close enough for rung joints.
DSCN3180.JPG


The Ash was 70mm high 15mm thick cut at a compound stock angle to get the slope. (20mm top 6mm bottom)
 

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andersonec

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CHJ":3g1qgz96 said:
mickthetree":3g1qgz96 said:
.....The mitre saw is still pretty new. I've not used it very much and the blade was one of the better ones these saws came with. I'm sure a mitre saw isn't the right tool for cutting fine mitres for boxes, but its all I have and I wanted to try it.....
There is no reason a mitre saw should not produce accurate mitre angles, mine is a budget end Rexon with a decent blade fitted and it nails my segment angles close enough for rung joints.
Chas,
It's not about cutting accurate angles, they can all be adjusted to cut accurate angles, it's about a slight curve appearing on his box side mitres when cut on the crosscut saw which is caused by the wood moving whilst being cut.

Andy
 

CHJ

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andersonec":2u3dta44 said:
...Chas,
It's not about cutting accurate angles, they can all be adjusted to cut accurate angles, it's about a slight curve appearing on his box side mitres when cut on the crosscut saw which is caused by the wood moving whilst being cut.

Andy

See my first post :)
CHJ":2u3dta44 said:
How positive is your stock location against your fences ?
 

andersonec

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CHJ":ors7ud5k said:
andersonec":ors7ud5k said:
...Chas,
It's not about cutting accurate angles, they can all be adjusted to cut accurate angles, it's about a slight curve appearing on his box side mitres when cut on the crosscut saw which is caused by the wood moving whilst being cut.

Andy

See my first post :)
CHJ":ors7ud5k said:
How positive is your stock location against your fences ?

Seen! #-o #-o #-o
Andy
 

mickthetree

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Wow! I didn't realise it was capable of doing that. I'll have another go with it later today using the hold downs that came with it. They are quite substantial.

Cheers!
 

mickthetree

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unfortunately the hold down does not fit when the saw is set to bevel at 45°. I am conciously holding the work down hard now and that seems to have overcome the curves I was getting. However, I am still getting weird results.

Set and locked to 90° the saw makes a bang on perfect cut. 90° in both x and y axis.


Leaving the saw locked at 90° but tipping it over to bevel at 45° it then produces this.


Both cuts made with the same face to the fence and same way up. Angle mesured from the same side (even though the photos look like opposite sides).

If I adjust the saw to cut these mitres then it is going to throw out the 90° setting. Or does cutting a mitre exagerate errors in the setup? So setting it up to these will give me even more acurate square cuts? :)

Just learnt the alt code for degrees in case you hadn't guessed :) ALT+0176 = °
 

mickthetree

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Sorry, in case it isnt clear the second photo is showing a mitre cut on the end of the same piece of wood. Measureing for square across the face of the mitre.

The mitre itself is very close to perfectly 45° jus not square across the face.

Scratching my head.
 

CHJ

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Is your saw pivot arm in line with the base Horizontally, I.E is the saw travelling up or down across the cut.
 

Eric The Viking

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I'd say the weight of the saw is causing it to cut slightly off true, coupled with what Chas says - it's addressing the wood asymmetrically and will therefore tend to pull one way or t'other.

I have the same problem with my own EB 300, and it makes a huge difference how I pull/push the saw on bevel cuts. Even mitres tend to be inaccurate unless I'm very careful. To be honest I haven't mastered the technique really, and tend to clean things up on the shooting board.

One test might be to see if you can vary the effect by pulling/pushing the saw in a different way. If you can, it's down to technique and slop in the mounting rather than setup as such.

Watching with interest.

E.
 

mickthetree

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sorry, I missed your post disco monkey. Yes it is a lovely place! ITs becoming quite pricy though so we may have to move out to the sticks a bit more. Although that may mean a larger garden and therefore a larger shed :) :)
 
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