Getting the mitre guage dead-on 45 ?

[Niki]

More playing with this tomorrow. It's for the missus birthday, which is, er, tomorrow! :shock: :lol:

Happy Birthday to your wife Wizer

So........which new tool you are going to get as a present :roll: :lol:

niki

 

[johnjin]

The slot should be parallel to the blade but only because the board will be pushed into the side of the blade if not or pulled away from it depending which way out the slot is. The board would have a concave edge cut on it instead of being square with the base. The only part of the slot that is really being used is the part that is at right angle to the cutting point of the blade. If you think of the slot at 45 deg to the blade you will see what I mean.

Hope this helps

John

 

[MooreToolsPlease]

best way to test for 45* is to use 4 pieces of wood, using a length top cut the angle on all 4 pieces, after cutting pinch 3 corners together using a dog, the final corner will have the combined error of all 8 angles, adjust the angle to suit until you get no gap!

 

[newt]

Matt I agree that it would be the edge of the teeth if the slot was as in the sketch below and the teeth at the back of the blade if the slot was in the other direction. All I am saying if the relationship of the blade to the slot was out be a small amount it is not going to affect the angle of the cut.

 

[newt]

Roy and others are correct in saying that the slot must be parallel with the blade ( for lots of other reasons it must be ) if you use the plastic triangle as a reference. If say the slot was out by 1 degree and you set the 45 degree reference against the blade and then adjusted the mitre gauge to the other edge the the mitre cut would be in error by one degree. All I was trying to say that in isolation the slots reference to the blade does not have a direct effect on the angle of cut. Sorry to be such a bore.

 

[OPJ]

Wizer, this may or may not help but, I usually find it helps to clamp the workpiece and slide the stop up to the other end - if you haven't tried that already, of course. :wink:

Personally, unless you're using something like an 80t blade, I'd always look to do any final trimming with your shooting board. If you have to shave a hair off, it's gonna be much easier than trying to do it on your saw too.

 

[Steve Maskery]

If a cut is out like this it is often becasue the workpiece moves slight. The forces on it are considerable so it needs to be clamped securely.

If you don't have a Wixey, do you have a Sine Bar. It's easy to get any angle, but it does require some maths, and if you say that isn't your strong suit then perhaps that's not such a good suggestion!

S

 

[misterfish]

If a cut is out like this it is often becasue the workpiece moves slight. The forces on it are considerable so it needs to be clamped securely.


S

I bought a decent Kreg aftermarket mitre gauge for my table saw and in the instructions they strongly suggest that you fix strips of fine grit sandpaper to the pushing face of the gauge.

When I first got it I didn't bother and had movement problems. I used double sided tape to face the gauge with 320 grit sandpaper and the problem went away.

Misterfish

 

[Steve Maskery]

The other thing we've not talked about is the importance of section length. It's not sufficient for all the corners to be cut accurately at 45 degrees, opposite components must be exactly the same length, too, if corners are to be tight.
S

 

[Chris Knight]

Adding to Steve's point, the width of the pieces must be the same if 45 degrees is used for the mitre otherwise a different mitre angle will be needed for a square corner that meets properly inside and out.

 

[wizer]

Thanks guys. I am about to go in the worked shop armed with this info.

To pick up on those last two point. The frame I made yestrerday was made from stock I planed up square and I used the shooting board to bring opposing sides equal in length. The frame turned out ok, it was out by probably half a degree

 

[Niki]

Steve and Chris, you are so correct...

That's the reason that my procedure to cut miters is

1. Rip the members on the table saw

2. Cross-cut every 2 opposite members to the same length

3. "Fine tune" of all the members to exactly the same width on the router table.

4. Cut the miters with the "miter sled" in the "Left & Right" method that will compensate for any small deviations from 45° and 90° and, using a stop at the front and not 6 feet behind me...

The 2nd and 3rd pics, are from the "Forbidden city"....

 

[wizer]

Yep, you guessed it. Failure.

I mucked around with the mitre gauge for a bit but couldn't get it spot on. In the end I decided to 'shoot to fit' as I was against the clock.

I managed to get a frame glued up. The plan was to break for lunch then come back, sand then finish. However, whilst sanding the phone rings, it's the nursery. Bubba has chicken pox!! So I had to go and get her, which means mummy's present (I was commissioned by my daughter) was not going to be finished! She's not home from work yet, I'm hoping she'll see the funny side :roll:

The good thing is I'll get some more time on it. I think next time I'm in the shop I am going to forget about making picture frames and get some MDF and play with it til I get the setting right. I think I'll shoot the mitres every time to clean them up, but it would be nice to have the gauge set dead on in case I ever need it.

Like Byron in his thread, I am wondering wether the sliding table is more of a hindrance than a help. I may try to make one of Niki's sleds to see if I can get on with it that way.

 

[MooreToolsPlease]

I've often wondered the same thing, one of the guys here used to have a robland panel saw, that sliding carriage was great for cross cutting big panels, dead accurate, nice square cuts, over ad over again.
Whilst I do admire peoples ingenuity for applications of a table saw, for picture frames I would always use a mitre saw.
One of the windows I make in my shop is made solely from mitred joints, with reinforcing chevrons, for that I have a non sliding mitre saw and length stop. I do keep eyeing up a double headed mitre saw, but for the amount I do my current method will suffice.

 

[wizer]

hehe I didn't even consider the SCMS. I am going to see how accurate I can get that. However, I'm seriously thinking of getting rid of it to free up some space.

Sliding tables are very useful with large sheet stock, but I wonder how useful they are to the woodworker/furniture maker?

 

[MooreToolsPlease]

I think they are as useful as the individual needs them to be,
If you dont have a mitre saw, then the sliding table would be very handy.
A guy here had a batch of tool boxes to make, and uses the sliding carriage to make rebates for the corner joints, but that was as much as he used it for.
One thing I have always wondered about given the usual space restrictions of the home woodworker why so many people use them, especially as they need space at right angles to ripping.
I suppose this just depends on the length of pieces involved.
Personally my table saw is just for ripping, 28 tooth 16" blades, gets used heavily day in day out, from ripping 1/2" beading down to width, or 4" hardwood. For cross cutting I have a radial arm saw.

 

[devonwoody]

Wizer, I would not suspect your setting up gauge is out, it is most likely to be the timber has not been held down tight enough when it passes the spinning blade, that blade will move anything if it can.
Or some movement on the glide mechanism when on your T/S.
Or timber stress, or poor quality blade.

Whatever method you use you need an end stop at the other end of your moulding so that every piece of timber is exactly the same length or else no expensive gauge is any good.

Its nice when you get everything right though.

 

[Big John]

There's a video on the woodsmith website on setting up a table saw for mitres. It's well worth a look. I think this is the correct link http://www.woodmagazine.com/bettertv/?c ... 1827891204

 

[wizer]

Thanks I'll have a look at that.

I was actually awake last night thinking about this. I have had a couple of ideas. I'll either do it or draw it later to see if it's going to work.

 

[p111dom]

I can't remember the last time I used the mitre saw I always use the sliding table. As for set up as other have said the important thing is making sure the table is sliding perfectly in line with the blade. This I found pretty easy to set. I have a dial cailper with a magnetic base. I just stick it to the sliding table and adjust with little knocks till the dial reads the same across the blades length. Next is to make sure it's cutting at 90 degrees. I think someone has mentioned this but I simply cut a length of MDF then turn over one half and check for any gap with two pieces against a straight edge. Once its at 90 degrees you can cut a square or rectangle of MDF. As for the mitre again it's a long length of MDF cut at 45 degrees according to the mitre fence scale. You can then check how much its out by aligning the two pieces with the edges of your MFD square. No more than a quater turn on the 5 dergee stop usually sees you get useably close within three cuts. Then you can use the length stop to cut four pieces with mitres on all sides and clamp these together to check the fit. It will probably be out slightly. The problem is that for a four sided picture frame if the angle is out by as little as 0.2 of a degree, by the time it gets all the way around it's out by 1.6 of a degree which you will see. For one cut you won't see visually that it's out by as little as this so you need the test cuts to show it. All you need to find out is whether the angle needs to be increased or decreased. The stop screw sometimes only needs to be rotated by as little as a 12th of a turn to make the difference. Just don't move it too much in one go and you'll get it.