Mitre Saw Levelling

A while back I installed my mitre saw into a recess in my workbench. All was good and the saw was level with the bench on either side.

I needed more bench space so I installed an electronic ram underneath and hinged the platform to allow the saw to drop below the level of the bench, like a flip-top but I'm lazy.

When it was all back together, the saw was sitting a little lower and not level with the bench, the wooden area under the saw had sagged a little due to the central support rather than screwed in from all sides. This was going to result in 1 of 2 outcomes:

1. all of my cuts would be a little crooked
2. The wood while under downward pressure would bow and bind on the blade, this is not super dangerous in the mitre saw but a bind or kickback is never desirable.

I didn't want to take it all apart again so here is how I set about leveling it all out using some threaded inserts and bolts with lock-nuts.

Step 1: How Bad Was It?

From the images, you can see that the saw was sitting several millimetres lower than the worktop and what was worse it wasn't level, this made for crooked mitres and it was dangerous to use as the wood started to bind when cutting and it collapsed into the drop to the bed of the saw.

Step 2: Preparation

I removed the saw from the recess.

When the saw is flipped over I found a nice consistent flat spot close to the mounting hole.

Using a reference distance from the mounting hole, I drilled an 11mm hole for the insert.

The inserts were threaded in from the top of the work surface, they are 10mm deep and the timber is 18mm, the reason I went from the top is that the force will be applied downwards, the insert will push against the top. If I went in from the bottom there was a risk of bursting out of the plywood under the force.

Step 3: Levelling

I threaded in some M8 bolts pre-fitted with nuts from the bottom, the nuts would be used to lock the bolt in place once the levelling was correct.

I reinstalled the saw on top and loosely fit the anchor bolts.

I threaded the levelling bolts up and down while maintaining some tension on the anchor bots until all was level in both axes.

The straight edge confirmed that I was flush with the worktop.

I carried out a number of cuts, rotating a block and cutting from different faces and testing the fit was straight afterwards. There is still some tuning required on the saw itself but this is an adjustment of the fence rather than the relationship between the blade and the bed.

Comments

[gregwest77]

I like the way you went about solving the problem. And making it adjustable is great. What I don't understand is why you just didn't put another piece of plywood or hard wood the needed thickness to resolve your problem. But seeing that you just might be a perfectionist like me I think you did a great job on it. Being a perfectionist can become it's own problem at times :-)

[Left-field Designs]

Good question, there were a number of reasons for this method.
1. My shop has no heating or insulation so the temperature and moisture change through the year does have an effect on my fully timber workbenchs.
2. My benches are made from really crappy low quality shuttering ply as when I built them I was on a small budget.
3. The saw is on an electromechanical lift as I have a serious back problem and cant lift it up and down, this ram was a cheap Chinese unit and isnt always consistent with it's stop position
4. This technique is much easier to fine tune in multiple directions than using fixed shims such as sections of ply

[gregwest77]

Ok, I understand now. Sorry to hear of your back problem. I myself have arthritis in my hips and back so I know where you are coming from. You mention your shop has no heat or insulation ? Does it have a good south facing side that gets a lot of sun during the fall and winter ? Thanks for getting back to me :-)

[Left-field Designs]

I do have a south facing wall, I am planning a passive solar heater as I previously built in this inscrutable: https://www.instructables.com/id/Beer-Can-Solar-Space-Heater/

[biosonar1]

You might want to think about putting some metal plates under the boalt bottoms to prevent the ends from deforming the plywood over time. Would require less frequent adjustment.

[biosonar1]

I miss-read your plans and thought you were just using the screw ends planted against the plywood and the inserts where to go in the feet of the saw, not the plywood. After rereading I discovered my mistake and realized you had a much better design than I first thought (so much for speed-reading). I like your improvement for leveling the saw very much and I am now upgrading my cut off saw to match! Very good design! Thanks for you response. I'll be slowing down my skimming of articles!

[Left-field Designs]

No worries, glad the article is of some help :-)

[Left-field Designs]

I dont understand.

[Berquin]

Hello,
This seems to be a very interesting way to do the leveling. However, my English is not perfect and I did not very well understand where and how the adjustable bolts with their nuts are installed (step 3).
Would it be possible to add a picture with those adjustable bolts in place?
Thank you.

[Left-field Designs]

I'm sorry it's not clear, without stripping the saw back off it's not possible to photo them in place. I will try to explain: I installed threaded inserts into the base the saw is mounted to, these are as aligned to flat spots on the casting of the saw table base. I loosely installed the saw on mounting bolts from the top, then added the adjustment bolts from the underside of the wooded base to push the saw up and against the mounting screws, this allowed 2 axis adjustment before locking the saw in place. The nuts then acted as lock nuts to stop the adjustment bolts coming undone. I hope this helps

[Berquin]

Thank you for the explanations. It is more clear for me now.

[alanjones]

I am a carpenter with about 40 years experience under my tool belt. I have built many mitre stands and made thousands of cuts. I never make the table of the saw flush with the extension wings to right and left. Always make them a few mm lower. Wood is rarely straight and the tables are for weight support, not alignment. Similarly, the vertical fence should be set back a little for the same reason. People with a machinist's approach are doomed to frustration. BTW I was trained as a machinist but left that trade due to working conditions.

[Left-field Designs]

Good to know, I was going for equal as to me it's what made sense, I mill all of my own lumber so it's usually freshly jointed and flat but I take the point. I this case the saw was lower than the wings and that was a bad situation

[MaC41]

Great job,but...
IMHO your only reference surface when working a Miter Saw should be the base+fence of the miter saw.Adjusting this to make accurate cuts is vital and there are very good Yutb vids on how to setup your machine.This is step one and is vital.

Once your machine is squared,just rely on it.
Relying on a bench to feed your stock will often give crooked results because long wood stock is most of the time warped.
Horizontal support+stop blocks,movable and clampable to the bench are all you need to work longer lenghts of wood,the saw can sit clamped on top of the bench.
You can unclamp and remove this setup in seconds,freeing the bench for other work.
I learned this from others, i'm no Newton :)

[Left-field Designs]

Agreed for the most part, my problem was that the saw had dropped below the bench top and so the bench was causing 2 issues:
1. Accuracy, where the top was not aligned with the saw and I was getting an off plumb cut
2. Safety, the cut was closing as the piece was not resting on the bed of the saw, as I cut the piece closed on the blade binding and making a dangerous situation

[yrralguthrie]

I understand where you are coming from leveling the saw. But it might better explain the situation if you used a different approach and different words.
Leveling the saw or the table it sets on is not necessary or even a useful objective. Neither needs to be level. They do need to be in alignment with each other. Place a straight edge on the saw as if you were going to cut it. Then adjust the saw (with shims) until the straight edge is supported equally by the two sides of the table and the saw. This will allow very precise and correct cuts. It is quite easy to align the saw to the point where a .001 shim cannot be slid between the board and the table and saw. If the board is only 4 feet long that would give you a 90 degree cut within 4.1 x 10 neg 5.

[Left-field Designs]

I see what you are saying and levelling is not what was achieved, alignment was. Thank you for the correction

[operabuffo719]

Do you have any photos showing the inserts in place and the adjusting screws and the surface they bear on? I am not sure how this scheme works though I get the concept. Can you show more detail please?

[Left-field Designs]

No unfortunately I don't, I can tell you they push up against a flat section on the bottom of the saw base casting. Without taking the saw off again this would be hard to show

[naic98]

Made it perfectly adjustable