Thread: best way to make accurate mitres?

A Ryobi sliding mitre saw is never going to be accurate - It's only good for framing basically where a couple of degree does not matter. There is so much flex in the saw and there is too much play in its mitre setting. Basically, none of the cheap compound mitre saw is good enough. If you insist on a mitre saw, you have to go upmarket to about the a grand mark to get a decent saw, which in my view is not necessary just for box making.
There are a few inexpensive options, all involved doing it by hand if you don't own a table saw.
1. Like you said, use the mitre saw for rough cut, and finish your bevel cut with a shooting board. You could use a sanding block instead of a plane.
2. Use a hand mitre saw, and Nobex is the best. Or if you are cheap like me, one from carbatec might do it for you. I picked up a 2nd hand precision brand mitre saw for 10 bucks on ebay.
3. Just do it by hand, it's actually not really hard. I find it easier with a japanese pull saw. Mark the piece all around, and try only cutting along the line that you can see. In other words, you starting cutting by pull the saw downwards along the line in front of you so your saw line is sloping downwards. Then you turn the piece around in your vice and repeat the process. Now you get cuts on both sides of the board along the lines. Once your saw is in the grove, it's a matter of keeping your cut along the lines.
4. Make a mitre box using 3 above. With a Japanese saw, the work piece should always be behind the slot so as you pull the saw through, you are cutting at the desired mitre angle. Bought mitre boxes are too loose for accurate cuts.

Unfortunately I have to agree with justonething in regards to the Ryobi sliding mitre saw.

I too started out with one of these and for the reasons outlined above (flex in the workings of the machine) found it a frustrating exercise to get accurate mitres. I ended up purchasing a table saw (i was looking anyway so this just gave me an excuse to hurry up).

Bets of luck.

Steven.

I did suspect as much, but considering I pulled it out of a skip and it cost me about $4 for some brushes from ebay, It's not really money lost.
That does also mean it has done a LOT of work in the past, which probably doesn't help much.

I'll have a look at those mitre saws, they look handy.

cheers guys

As the other guys have said ,plus my own grumpy opinion.
Accurate work involves careful stock preparation ,especially on small items.
Accurate ,marking out and a solid bench to work from.
Mitres are tricky things ,I first cut to my line with a good hand saw on small items.
Then I would be either using a well tuned hand plane either a number 3 Stanley or block plane ,these are my favourites but not necessarily the best or the worst there just what I have .
Even a flat hard board with 80/120 grit sand paper attached can be very useful for taking that last smidjing off.
But it is just practice(saw dust on the floor)

Matt

Hi Stiffman,

I see that you are at a similar stage to me in box making (ie just starting). I have made a few small boxes with mitres in the corners and I made the mitre cuts on my Ozito sliding mitre saw - very much a budget priced saw. I have owned the saw since new and I took the time to make sure that the blade was cutting square to the fence and perpendicular to the saw bed. I was able to do this quite accurately with known good squares (rafter square and machinist square). Even though I am far from experienced in box making, I was able to make quite good joints using the following steps (I won't be offended if corrected on my technique by experienced woodworkers).

I was able to use a table saw at the local Men's Shed to rip the box sides and then run them over the jointer. This ensured that I at least started with good parallel stock for the sides. Then on my Ozito, I clamped the stock and made the first 45^ cut (cut in the horizontal plane). I used a stop block to get the side length correct and then with this side clamped made the second cut (making sure not to jam it between blade and stop) and continued without changing the angle of the blade. Hope this makes sense. I have included a photo of my most rencent box and you can see the mitres. Now this is not a perfect box, but I can tell you that it is better than my two previous efforts. The 'wood' by the way, is 10mm bamboo flooring that I purchased (on clearance) at Bunnings.

Good luck with your efforts and who knows the two of us may be posting some quality boxes after a bit more experience. Tim

image.jpg

Another vote for a shooting board from me ! Have a look on eBay for a #5 1/2 or preferably #6 Stanley plane. They are not quite as common as #4s, so you may have to be patient. Hunt around the web for shooting board designs. Paul Sellers is a good source. For the bevels on the long edge a different add on is required. I made myself a special bevel shooting board and it's very very handy and therapeutic at the same time.

Hi Stiffman,

There are two main areas where things can go wrong ... The ANGLE of the cut and the LENGTH of the box side.

The slightest of uneven sides will show up as unmatched corner joints even if your angles are perfect!!!

I use my mitre saw for box mitre making where the timber with is <10mm. This is because the small gaps are virtually indistinguishable in such small mitres.

When using the mitre saw there are a few things that you can do to get a better result.

Firstly, calibrate the saw ... I have a ""square corner tray"(dont know how else to describe it). It is a simple piece of 12mm MDF (400X700) with a 35mm strip wood screwed to the face on the top and also down one side
I also have some 200 MDF triangles made up with 2 x 45 and one 90 degree corners. When I put then in the 90 degree corner of the tray they match perfectly. It takes some time to get them perfect but once done you will find this apparatus most useful for all types of things (If you wax the surface you can safely use it to do glue ups of boxes, doors etc. I use this tray box to check the angles of the cuts. There are loads of videos on Youtube that show how to calibrate a mitre saw ... personally, I used masonite sheets (200mm by 100mm) cut a few mm off and test in the square corner tray. When you are sure it is square ... move to 45 and do an angle cut across the masonite, and again try them in the square corner box. Keep doing this until you have it perfect (takes a few goes and remember to chalk mark the cut side for reference).

Secondly, use a tall backing board secured by a clamp against the saw's fence, and a stop block (with opposite mitre) clamped to the backing board.

Thirdly, You may have very strong hands but not as strong as a clamp ... and the slightest movement will ruin the cut. I use a stop block on all my box cuts as then the lengths are identical.

Fourth If your saw can be locked to be a chop saw then lock it. Watch your grip of the saw and move strait down ... no sideways pressure alt all.

For thicker material or frames I use an Incra miter 1000 on the table saw, with an 80 tooth rip blade.

Remember, even if the mitre saw cuts at 42 degrees then the offcut will be 48 and if you think about it you may be able to get away with inverting the ""off cut"" to achieve a perfect 90 degree joint!!

Happy boxing

Regards

Rob

Originally Posted by Tahlee

with an 80 tooth rip blade.

That'd be a crosscut blade, not rip, yes?

Originally Posted by aldav

That'd be a crosscut blade, not rip, yes?

Yep ... thanks for the correction.

Hey Stiffman
Here are pics of my tray that i mentioned above .. and the 45's ... it is great to have this devise as it sure makes checking corner angles clear.

The last pic shows (nearly) perfect angles ... but this outcome was made on the tables saw

IMG_0102.jpgIMG_0104.jpgIMG_0105.jpg

Regards

Rob

Good Morning Stiffman

From your posts I am assuming that you are relatively inexperienced, have limited tools and machinery, but are having a go and keen to develop your skills and knowledge. Great. We have all been there!

In the pantheon of woodworking the creation of small boxes is frequently considered to be fine woodworking; a sliding mitre saw (any brand) is a bush carpenter's machine. It can never be a precise tool, but you can minimize its inaccuracies. You might like to consider the following strategy:

FIRST: Tune your Ryobi as suggested by Rob above. Also clean and sharpen your blade - it should be almost a dull mirror finish. You will then be able to rough out box components.

SECOND: obtain or, preferably, make a "donkeys ears" mitre box. There is excellent advice on forumite Derek Cohen's website - In The Woodshop . This will allow you to refine accurate 45* bevels.

THIRD: As suggested by Rob, use a stopper. This will allow you to ensure that both sides are exactly the same length - to within less than 0.1mm - a slight inaccuracy will force the mitre open. Ditto, front and back.

FOURTH: Practice on cheap material - pine or any scrap that you have on hand. Not MDF as the resin blunts tools including plane blades real quick.

Good luck, and enjoy the journey.



Fair Winds

Graeme

I've just bought a huuuuge carbitool chamfer router bit with the intention of using it in the router table.

First by cutting the peices to length ~+2mm (as plain 90^ cuts), then using the fence on the router table adjusted to take only a 0.5mm off per pass, how do you think that would work? Ok? (I'd use a mitre gauge and backing piece to make the first few waste removal and then fine finish cuts)

I ask as getting 45^ on my table saw for box mitres is impossible. The blade simply refuses to go to >44.9 and the gap is hideous. As the chamfer bit is a perfect 45, I thought a few sneak-up trim passes to the line would work wonderfully.

As the bit has a bearing and the RT's fence can be made to exceed that by the slightest hair it seemed a nice way to get a precision 45.

Is my logic reasonable?

I'd love to start making mitred boxes.

Cheers guys,

Yea graham, I guess i'm fairly inexperienced, most of the woodworking I've done would be considering butchering wood to most of you.
I don't really have any stationary machinery as of yet, beyond an old crappy drill press and the mitre saw, which makes doing much more difficult.

Jointing isn't something I've worked out properly yet either. I've been using dressed timber from bunnings to try to cheat that for some of the messing about I've done, which seems to work OK, but is far from ideal.

Tahlee, that looks like a very useful setup with the board and corner blocks. I think I'll have to have a go at making something similar.

I'll have to take all your advice and try to tune the saw a bit more, but not expect perfect results. a shooting board seems like a good idea.

Cheers,
Matt.

No mucking around when doing boxes, you need this https://www.youtube.com/watch?v=3ruwZdaPjbs