My Portable Wide Slab Flattening Jig

[SkinnyB]

Thought this may be of interest to some people....

I required a way to flatten a wide slab for a large live edge table top (2.3m x 900m) that I have been asked to make.
Looking at some designs of just screwing 2x4s to the side of the slab... I was looking to make something a little more polished/reusable/flexible that could be used multiple times and take up a small footprint when being stored.

My main points I wanted:
3m long x 800mm wide
Portable
Adjustable for different sized/thickness timbers
Work holding clamping system
Fast setup
Ease of use
Work levelling system
Small footprint when stored
Dust Extraction
Easy to level/coplanar.

This is what I ended up creating:

IMG_4196 by jamie skinner, on Flickr
IMG_4206 by jamie skinner, on Flickr

The main parts consist of:
2x Evolution mitre saw trestle stands
2 x 3m laminated plywood guide bars
1 x router sled

I chose multiple pieces of laminated plywood as it will be more stable than a regular softwood 2x4.
Managed to make the whole thing from a single sheet of 18mm Birch ply which was pleased about. So only cost me a days work and £50.

The guide bars are attached to the trestles via a sliding dovetail system. This enables me to mount the trestles to any point along the length of the guide bar depending on the timber to be flattened.
IMG_4195 by jamie skinner, on Flickr

Mounted via bolt from underneath. I originally had planned to use a knob instead of a nut in my original design. However due to this central bar in the middle there is only just enough space to get a nut in there.
IMG_4194 by jamie skinner, on Flickr

Original designed pieces:
IMG_4189 by jamie skinner, on Flickr

Modified to fit as there was not enough space for the full sized hooks. They need to spin 90 degrees to go under the bars.
The mounts are made from plywood with a 3d printed dovetail slider with captured bolt.
IMG_4191 by jamie skinner, on Flickr


My initial design to hold timber on the trestles are like so:
IMG_4205 by jamie skinner, on Flickr

And clamp like this... (Bottom right) The holes are for screws if needed.
IMG_4206 by jamie skinner, on Flickr

To make each guide rail coplanar with the other I took inspiration from Marius Hornberger (Link)
He uses two strings attached at each end with cross diagonally. then lifts one string up by a few mm. The strings must they lay onto of each other but not touch. This can be adjusted by raising each leg of the trestle in my version until the strings are above one and other.

Strings attached:
IMG_4202 by jamie skinner, on Flickr

Raised the top string up by the width of one string using a nail.
IMG_4203 by jamie skinner, on Flickr

Strings are on top of each but do not touch. Each guide rail is now coplanar with the other.
IMG_4204 by jamie skinner, on Flickr

The router slides back and fourth on the sled.
IMG_4200 by jamie skinner, on Flickr

IMG_4201 by jamie skinner, on Flickr

The sled is attached to one rail with two pieces of Plywood. A sliding fit enables the sled to move freely left and right but without to much play.
IMG_4197 by jamie skinner, on Flickr
IMG_4199 by jamie skinner, on Flickr

1st test:
1.I had a little issue with the router that seemed to lower the router bit further into the work is I went. I guess I must not have locked it down enough.
2.The router moving forward and backward wasn't as friction less as I hoped. Fixed by sanding it a little wider where the plastic router base goes and then adding paste wax.
3. Work holding isn't great. The clamps I made work great as stops but I need a way of clapping the timber down.
4.Knobs on clamps are too big.

Router dropped:
IMG_4207 by jamie skinner, on Flickr

I was very happy with the cut finish I got:
IMG_4208 by jamie skinner, on Flickr

I then spray vanished everything with Ronseal clear varnish to protect it.

2nd test: (This was on the actually piece/s)
Weight of the timber (Oak 80mm 2.5m 700 wide) was enough that I felt I didn't not need to secure it.
The piece had a slight twist to it which I shimmed out using some this wood under it. Using a straight edge running across both guide rail I measured down until I had and even amount to remove of each side. I need to design an adjustable system where I can lift/hold each corner of the timber to shim out the twist.

All went pretty well although....
I had the chuck come loose on the router... Which meant the bit plunged deeper that I wanted. Luckily it was just above the final pass once I had finished so was fine.
I also set my Erbauer router on fire...Was my favourite router for all my hogging out/rough jobs. It had worked hard I think maybe running it at a low speed means the internal cooling is not as great so burnt out.

Picked up the 'new' style Erabuer router from Screwfix... What a pile of crap they are... Locking system still allows router to move up/down by 2-3mm. So much play in the plunge mechanism. Base plate screws weren't countersunk into he base enough and stuck out... And finally after 3 minutes attached to my jig also caught fire... Returned It!

The 80mm slab has been flattened to 60mm due to the cupping of the board. I could have cut the board in half and the flattened it but wanted a complete slab. An extra price will be joined on to this to being it to the 900mm final dimension.

IMG_7146 by jamie skinner, on Flickr

Just need to flip it over and repeat and flatten the other section which gets glued on.
IMG_4267 by jamie skinner, on Flickr


How I made the jig:
Each guide bar consists of 3 layers of 18mm birch plywood. To make the 3m length I added a piece on the end and over lapped the glue join with the next layer creating a strong single length piece. The two outer pieces are run through the router table with the largest dovetail bit I had.

IMG_5213 by jamie skinner, on Flickr

The outer pieces are drilled and countersunk ready to receive screws. To get a straight edge I used the straightest 2x6 I had which was neigh on perfect. I used this to align and clamp the plywood to as I was gluing/screwing it together.
IMG_4173 by jamie skinner, on Flickr

Assembled like so:
IMG_4065 by jamie skinner, on Flickr

IMG_4174 by jamie skinner, on Flickr

IMG_4176 by jamie skinner, on Flickr

Next layer glued on and clamped to 2x6.
IMG_4178 by jamie skinner, on Flickr


Assembled:
IMG_4181 by jamie skinner, on Flickr

Two guide rails made.
IMG_4182 by jamie skinner, on Flickr

I clamped both guide rails together at one end to see how straight they are. I got 4mm gap at one end over 3m which I am happy with.
IMG_4183 by jamie skinner, on Flickr

Started to put it together:
IMG_4193 by jamie skinner, on Flickr


To do:
1. I need to add a dust extraction system. I will be making a small version (1m long) of this to use in my workshop on projects so want extraction for that.
2. I need to make some levelling feet for the trestles asI just used some pieces of wood to get the right level. Adjustable feet will enable me to dial it in more.
3. I need to make some brackets to hold it not the wall for storage.
4. Get a heavy duty router for this purpose.
5. Adjustable under trestle support for timber to allow for holding twisted timber.
6. Wind up string holder to store string for each time it is setup.
7. Invest in a replaceable insert flattening router bit.
8. Improved work holding/clamping system.

I hope you enjoyed my post!

 

[MikeG.]

Did you consider making this for an electric plane, rather than a router? I've never really understood why people use a router for the job with it's small cutting footprint, when there is a tool actually designed for hogging off large amounts of timber.

 

[Trevanion]

Did you consider making this for an electric plane, rather than a router? I've never really understood why people use a router for the job with it's small cutting footprint, when there is a tool actually designed for hogging off large amounts of timber.

That's actually a pretty neat idea, I would guess you would have to take the beds off the planer to give yourself clearance and figure out some way of attaching it that also allows it to traverse back and forth as well as travel along the workpiece without being too clumsy. I imagine it would be far quicker than using a 1" bit in a router, probably less messy too as a planer can throw shavings down an extraction hose pretty well.

Or you could get one of those Makita 12" hand planers and do a couple of passes :shock:

 

[Fitzroy]

I like that and thanks for all the detail on your thought process, I have need of flattening a few big boards soon and will defo take on a few of you ideas.

Fitz.

 

[will1983]

Have a look at videos made by Sampson boat company, they built a jig using the monster Triton electric plane for just this purpose.

If you want to stay with the router look at getting a 2" bit from Wealden tools, that's where I got mine from and it works great.

For holding the piece tight look at cutting some spacer blocks slightly thinner than your finished thickness. Place them between the rails and the work and then clamp the whole lot together with a couple of sash clamps.

Alternatively could you make a pair of 'topper' timbers that sit transversely across the top of your two saw horses. You could make these wider than the saw horses for wider stock and design is so the rails can sit on top of the toppers. This would allow you to insert packers to level your rails.

 

[Yojevol]

Have a look at videos made by Sampson boat company, they built a jig using the monster Triton electric plane for just this purpose.

Just had a look at the Sampson video and it became obvious to me why a router is more appropriate than a planer for a small jig. You need some sort of mechanism for lowering the cutter after each cut. The router inherently provides this as part of the machine. For a planer rig a mechanism has to be built into the jig design. It can be seen in use on the video.
A planer may give a better finish (probably not too important in boat building), but on the other hand may be vulnerable to tear-out. A router finish is going to need further work (smoothing plane, sanding. scraping) to get a table top finish.
Brian
PS the star of the video appears right at the end

 

[scholar]

Have a look at videos made by Sampson boat com
A planer may give a better finish (probably not too important in boat building)

I have got hooked on the Sampson Boat project.

The finish from a planer may be slightly better, but the thing that has struck me from watching the videos is the precision applied on the whole boat construction - quality furniture grade fit.

Cheers

 

[Hornbeam]

I like the sting method for ensuring the 2 rails are parallel ( had to convince my self on a piece of paper) The only issue is it that while it ensures they are parallel they can be at different heights so you could end up tapering the slab
Ian

 

[Yojevol]

I like the sting method for ensuring the 2 rails are parallel ( had to convince my self on a piece of paper) The only issue is it that while it ensures they are parallel they can be at different heights so you could end up tapering the slab
Ian

That's the 'sting'

 

[will1983]

For long narrow slabs the string method is less effective than for shorter wider slabs.

For this reason I always use a pair of winding sticks (2 decent quality 4 foot levels) to set my jig up.
They also give you a quick reference datum to measure down to the jigs bed for setting the height.

I also like to check the twist at a few points along the length of the rails, I know the rails are straight so this is really a double check that nothing has developed a warp or bow since it was last used.

 

[SkinnyB]

will1983 - Thanks for the info! Great channel and have subscribed. The planer sled looked great! So I went to Screwfix Friday and emptied my bank account....

Spent Friday night and Saturday coming up with this:
IMG_4355 by jamie skinner, on Flickr

The planer is perfect as it has mounting options already with it. I used the 4 m6 screw points to mount the router to a parallelogram mechanism. Still not finished it yet. Quickly mocked it up before the rain came.

I can still plane down material from 110mm to 25mm thick which is good. I have however lost approximately 100mm width by using the planer. I have room on the sled to extend the guide bars out further but need to extend the trestles.

The router still mounts on though so I could always use that to trim the edges on wide slabs.

Still to do:
1. I need to add a threaded rod to be able to adjust the planer up and down.
2. Add some UHMW plastic to the sliding surfaces to reduce friction.
3. Add plywood to keep the small (1m) guide bars square to the long guide bars (3m)
4. I had to remove the old extraction shoot as it stuck quite a way out from the planer. So I need to 3d print a new one which directs chips straight up into a vac.
5. Mounted On/Off switch on sled.

IMG_4363 by jamie skinner, on Flickr

IMG_4362 by jamie skinner, on Flickr

IMG_4360 by jamie skinner, on Flickr

The parallelogram mechanism keeps the planer very rigid even at its lowest height. I made sure the plywood box it sits in has a good friction fit so the planer cannot move side to side.

Highest position:
IMG_4357 by jamie skinner, on Flickr

Lowest position:
IMG_4358 by jamie skinner, on Flickr

IMG_4359 by jamie skinner, on Flickr

Other points:
I wanted some smaller guide bars for smaller work so incorporated this into the design. Same dovetail system holds the two guide runners in place.

IMG_4366 by jamie skinner, on Flickr

IMG_4367 by jamie skinner, on Flickr

Planer left to right movement.

IMG_4364 by jamie skinner, on Flickr

IMG_4365 by jamie skinner, on Flickr


Build:

I started out creating some spacer blocks which can attach to the planer. One side has a 6mm clearance hole in which a 6mm cap screw will slide into.
The other side has a 10mm thread to allow a bolt to be attached. I may change this design later on once I see how this goes.

IMG_4332 by jamie skinner, on Flickr
IMG_4333 by jamie skinner, on Flickr

Cleaned and ready ti be oil blackened.
IMG_4335 by jamie skinner, on Flickr

Heating them up.
IMG_4337 by jamie skinner, on Flickr

Blackened.
IMG_4339 by jamie skinner, on Flickr

How the screws work.
IMG_4340 by jamie skinner, on Flickr
IMG_4341 by jamie skinner, on Flickr
IMG_4342 by jamie skinner, on Flickr

Parallelogram parts cut. I may change the plywood to metal later on depending how it goes.
IMG_4343 by jamie skinner, on Flickr
IMG_4344 by jamie skinner, on Flickr

Starting on the planer cage. 2 x 18mm plywood.
IMG_4347 by jamie skinner, on Flickr

Short guide rails and cage finished.
IMG_4349 by jamie skinner, on Flickr

Mounting the planer.
IMG_4350 by jamie skinner, on Flickr
IMG_4351 by jamie skinner, on Flickr

Mounted on the long guide rails.
IMG_4355 by jamie skinner, on Flickr

 

[MikeG.]

Excellent. Good decision, good design. We'll discuss my commission by PM, shall we? :wink: :lol:

 

[Nelsun]

Oh, I like that very much. The parallel-o-wotsit is a clever idea. I imagine it'd need a rock solid means of keeping it fixed I place?

 

[SkinnyB]

Finally got to a stage where I am happy to share my progress further!
Here a video of it in action:
https://www.youtube.com/watch?v=0TGM6HJcTOk&feature=youtu.be


Added easy adjustment to the rise and fall mechanism with the use of a threaded rod and some hand wheels. It has a adjustable spring for tensioning the planer depending on thickness.
IMG_4443 by jamie skinner, on Flickr

IMG_4526 by jamie skinner, on Flickr

Added a new 3d printed extraction port which is 100% efficient when planing at full 150mm width.
IMG_0375 by jamie skinner, on Flickr

IMG_4522 by jamie skinner, on Flickr

Brought some roller skates for the wheels and now the whole unit glides very easily.
IMG_4523 by jamie skinner, on Flickr

Added side bearings.
IMG_4524 by jamie skinner, on Flickr

This is the finish I get... This piece of wood requires 3 full width passes. joint lines are minimal if not none.
IMG_4521 by jamie skinner, on Flickr

Slab planed.
IMG_4527 by jamie skinner, on Flickr

Using the jig:
I can take off approximately 0.5mm - 1mm in one pass at 150mm wide.
The planer does get a little hot so I take regular breaks every 10 mins for 5 mins and leave a fan aimed at the planer which helps a lot.
I have the planer depth set at 0.5mm. This means this is the maximum it can take off in one pass. If I use the adjustment knob on the sled and lower it to much the planer lifts up and still only takes 0.5mm off. I then do the same pass again until it is no longer removing material.
Setup is about 5-10 mins.
The adjustable feet for the trestles help levelling considerably.
String method is working great!


To do:
Add an adjustable stop for setting the depth at a certain thickness. Used when I need two or more slabs the same thickness.
Round over and sand the sled.
Varnish all parts.
Source a longer hose for the extract.

 

[Nelsun]

That is some jig you've got there. Not sure "jig" really does it justice though!

What you gonna call it... Concorde?

 

[scooby]

Very impressive. =D>

Thank you for the indepth description and video.

 

[ColeyS1]

That's amazing!!!!!!!! Very nicely done.

Sent from my SM-G960F using Tapatalk

 

[Mattias87]

That is absolutely amazing. The work and thought that has gone into that has truly paid off, really well done.

 

[Suffolkboy]

Brilliant. Thanks for posting.

 

[memphis32]

I'm not convinced by the string method for levelling...

Consider that you set up the jig and check for level, finding the string touches in the middle - one of two corners needs raising to pass your level test, yet only one of those will make the jig closer to level, the other will make it worse.