Cross-Cut Sled Frustrations

[Harris84]

So, I'm quite new to woodworking, but today I felt pretty disheartened with what I was trying to achieve, to the point where I feel like giving up! I got to a point where I thought sod this, I'll just buy one, but then went down the mental track of "if I can't build this, I can't build anything so why bother".

Cutting to the chase (my first attempt at this post was a complete essay, which i later thought was unnecessary);

• My sled constantly sticking
  • While the original board looked fine, after cutting it (for the base and fence) I noticed there were bows in the cur pieces
  • It looks like when cutting the center of the board with the table saw (once the miter joints were in and fences were on but not squared), the board shifted/warped
  • Flipping the board over and running my hand over where the slot is cut, there's a significant lip on one side
  • I don't actually know if this is the issue, but I can't tell you how frustrated I was with a constantly jamming sled that would tip the table saw if I tried to work through it
  • This made the 2nd point all the more frustrating, as I was having to restart many cuts due to jamming despite constantly inspecting the back of the board and sanding to remove any proud points that may have been there.
• Squaring the fence
  • I had a bit of spare chip that I cut 2 sides on and then checked the corner with a square. It was pretty close, but I know 'pretty close' on a small-ish square on a single cut could mean miles off on a long sheet cut, so thought I'd check it with the 5-cut method
  • Cue multiple attempts at the 5-cut method, every one of the cuts being interrupted by a jamming sled!
  • I persevered and got to my 5th cut, and it was pretty wonky (23mm at the top, 19mm at the bottom, over a 447mm length
  • My calculations tell me a 21mm adjustment is needed. That feels waaaay too much considering most people are talking 1-5mm at most?

So I guess my questions/issues/rant points are;

• Should I just use aluminum t-track pieces for the runners?
  • I've seen a few recommendations for this, and although I wouldn't say my miter strips are a problem, I'm unclear if they are contributing to the jamming
• Is the bow in the board fatal, especially for a 'jig' where some level of accuracy is key?
• Does the 21mm adjustment seem viable, or have I worked that out wrong?

Obviously, I should just make the adjustment and see if it improves, but owing to the points on my sled jamming, I'm burning through wood at a rate of knots, and I don't think I (today at least) have the patience to see that through!

Feel free to tell me I've clearly messed up, and I should start again

 

[Lorenzl]

I have the same feelings but am persevering. For one of my jigs I brought aluminium guide from Ali express and they are a very good fit on my saw. How many guides do you have?

What material did you use for the cross cut base and how thick?

 

[Lorenzl]

I also have problems with a purchased mitre guide on my router table; t is a little bit loose. It is "adjustable" with screws that spread plastic washers. When I adjust the washers it sticks or the washers come loose when using it!

 

[Harris84]

Base is 18mm ply.
I noticed when laying it on the table to attach it to the miter strips there was a slight bow, which I hadn't seen (or wasn't there) as part of the full sheet.
RE purchased miter guides - I was hoping to get some that are fixed. I actually have 2x 400mm lengths of t-track that I intended to use on the top of the fence. They fit into the track perfectly so I'm debating just buying longer stips of that in case the strips are (even if only partly), my issue.

I'm just really not sure how to 'troubleshoot' a jamming sled.

 

[Trainee neophyte]

Is it the sled or the table? Do your slots have burrs or rust or something stuck in the chanel? Is the runner actually straight? Are the slots actually straight, for that matter, and parallel to each other? How much (if any) wax have you got on the runner and in the slots? Have you made a T-shaped runner to match the T-shaped groove, because then it could be variations in depth rather than the thickness. Also does it jam if you apply some sideways pressure -ie your runner could be too thin and allow sideways movement.. Finally, does it slide freely with the blade lowered, but only bind when used in anger? If this, then the blade may not be parallel to the slots. Any screws fouling the chanel, or distorting the runner? So many places to look for the issue. Perhaps start from first principle - get your saw set up as exactly as possible regarding squareness of blade to slots, so you can start eliminating reasons.

"Once you have discounted the impossible, then whatever remains, however improbable, must be the truth."

 

[sometimewoodworker]

Looking at your first post, the problems seem reasonably easy to understand though frustrating.

1) using material for the base that is not stable, plywood is not guaranteed stable, high quality birch ply maybe but even then it’s not guaranteed.

2) not shaping the runners to fit the slots, possibly along with the wrong orientation of the cut pieces so that wood movement can distort the slides

3) misunderstanding the way the 5 cut system functions.

answers
1) use chipboard or MR-MDF for the base as these are the most stable. Possibly even a piece of laminated board for minimum sticking

2) either buy commercial runners the correct shape, metal runners that are a good fit or shape good hardwood runners to fit

1a+2a) use paste wax liberally on the underside of the sled

3) the adjustment needed is 23mm - 19mm = 4mm / 4 so 1mm
i am assuming that the width of the strip is 23mm at one end and 19mm at the other.

Basically your current sled is valuable only as a practice piece and an example of why material selection is vitally important, it isn’t worth the time to fix as that requires replacement of everything apart from possibly the front and back fences.

the other point that hasn’t been addressed is humidity, if yours is fluctuating then you will continue to have problems.

 

[woodwind]

I used the 5 cut method but didn't bother with the calculations, a small adjustment each time will soon get you there.

 

[Chief Sawdust Maker]

I went round in circles trying to decide what to use and what type to make
Eventually I made mine from Moisture Resistant MDF with the exception of the runners to go in the slots I initially looked a cutting up a plastic chopping board but in the end went with Beech and spent a lot of time getting them to be a good fit.
I followed




and even brought one of his stops
Jonathan explains the 5 cut method really well and the best way to line everything up I am 100% happy with mine its bang on square (cant see any light when checking) and the Katz Mosses stop is well worth it
I was always a massive mitre saw fan until I built this but i am now a sled convert
Lots of wax is key and when things start to get a bit grubby or sticky clean off with spirt and start again

D

 

[Stevekane]

How about a photo of your Sled and the Saw, that might help the people get a get idea of what the problem might be?
Im interested because its something I also want to build and one of the things that caught my eye was the T Slots, in my ignorance I hadnt realised that the sled runners were also T Shaped, is that correct and if so it seems a recipe for jamming up?
Steve.

 

[Harris84]

I don't have a current pic of the table saw; the one attached was pretty fresh out the box from last year.
I don't use the blade provided (found it didn't rip too well and got very, very hot too easily), so I bought and use this one; Saxton Flat Top TCT Circular Saw Blade 255mm x 28T x 30mm Bore + rings fits Bosch Makita etc : Amazon.co.uk: DIY & Tools

The pic of the sled isn't great, and I suspect you want to see the back-side more than a top-down view, so I'll pop out later and get a better picture.

Link to saw if interested - Evolution R255PTS 255mm Electric Table Saw 230V

 

[throbscottle]

If it's any consolation, I made a CC sled because I needed it in a hurry -- I used a piece of OSB that had been leant against outside wall for a year, a shelf that had been in someone's garden for years and a strip cut from a bit of wood from an armchair that had also been outside for a year getting very soggy! So the guide warped after fitting it and jammed - that was troublesome, and the fence is bowed. However it's been sufficiently ok for my needs so far that I haven't got round to improving it. Long pieces are ok, small pieces I get trapezoids and parallelograms!

 

[Dynamite]

Hi Harris, i certainly wouldnt even contemplate giving up Just because you aren’t happy with it. I have got like that a few times and it’s pointless. We are beginners after all and we can’t just become master carpenters at the drop of a hat. Most learning comes from doing and mainly learning by mistakes.

put a positive spin on it and the fact you’ve found a few skills you need to hone, that’s all. Don’t forget we are in it for the positive effect on our mental health too.

kind regards Rob.

 

[graham88]

Hi Harris, I dont own a table saw so take any advice with a pinch of salt. Have you tried passing the runners through the slots NOT attached to the sled? If one/both start jamming at a certain point it might help you narrow down where to focus your efforts. I'd agree with previous posts about waxing everything up and using MDF instead of ply, especially if it has a side covered in melamine which can face down to reduce friction. As far as a general troubleshooting guide I would do the following (in order):

1. Check the runners move freely in the slots not attached to the sled and do not move too much side to side.
2. Check the saw blade is parallel to the slots and adjust accordingly if possible.
3. Check no screws or the insert are sitting proud and that the table and it's leaves/side panels (not sure of correct term) are flat.
4. Check the bow of the sled base without runners or the fence. Put parts back on one at a time and check flatness each time.
4. If these all check out, reassemble the sled and liberally apply some wax.
5. If it's still jamming I'd just make a new sled.

If anyone with some actual experience could possibly check this so I'm not talking utter rubbish that would be amazing. Tell me where I'm going wrong and I will amend as appropriate.