Slab flattening jig concept

[ChiknNutz]

On the heels of Woodpeckers new jig, I thought I'd post some pix of my idea I've started designing.  I have been wanting to build a better one than my sub-par MDF and lumber contraption for some time now anyway, theirs just got me a bit more motivated.  I know this is really overkill and you can get good results with far less.  Being a mechanical engineer, it is what I do.  This is based on a jig that will roughly accommodate a 4x8 slab.  The aluminum extrusions are standard 8020.  The linear rails are SBR20 and are available quite affordably on ebay.  Like any new design, there are details to work out.  As such, this is not a complete design, just a start in case anyone else needs a little kickstart too.

 

[rljatl]

My one suggestion would be to design it so that a standard router plate can used for the router sled.

 

[ChiknNutz]

Agreed, that was one thing I was driving towards, just had not visually implemented that.  Just to clarify, I currently have no intentions of making these for sale, just showing an idea I have kicking around.

 

[jpmeunier]

Incorporate a CNC dust boot to the sled, in my mind its one of the main benefits of the router being rigidly mounted.

 

[Svar]

Incorporate a CNC dust boot to the sled, in my mind its one of the main benefits of the router being rigidly mounted.

I use router's own dust port and add a flexible skirt on the bottom.

 

[jpmeunier]

I use router's own dust port and add a flexible skirt on the bottom.

That pretty much what I meant. I also added a port for a 4" DC to mine, works like magic.

 

[mbs]

Nice design.  Since it is so big are you going to push it by hand or use a motors/hydraulic/chain drive ...?

 

[Gregor]

As I don't have enough room for a jointer (big enough so it has a sturdy enough fence and enough distance to the walls on both in and outfeed sides) in my small shop I'm thinking about something like this - but adjustable in height over a wide enough (like 30cm) range so it would, through clamping workpieces to a vertical fence that is square to the top plane, give me an ability that the total available floor space denies me.

 

[Michael Kellough]

As I don't have enough room for a jointer (big enough so it has a sturdy enough fence and enough distance to the walls on both in and outfeed sides) in my small shop I'm thinking about something like this - but adjustable in height over a wide enough (like 30cm) range so it would, through clamping workpieces to a vertical fence that is square to the top plane, give me an ability that the total available floor space denies me.

That would be interesting but requires an additional device/design for work support. Which is needed anyway.

Too little thought is given to supporting slabs during milling. The final support structure needs to be simulated in supporting the slab during milling if the slab is intended to stay flat long term. (Or consistent in thickness) Which may be wishful thinking anyway with such a large piece of natural wood.

 

[rst]

I do not have pics, but I used DeStaco horizontal clamps in conjuction with shims that I adapted to attach to my MFT style work table (63" x 102" with removable cutting backer in the middle).

 

[ChiknNutz]

Nice design.  Since it is so big are you going to push it by hand or use a motors/hydraulic/chain drive ...?

Initially just all by hand.  By having fully supported rails & bearings, I thought about attaching a simple horizontal rod so you could just push the carriage along from one side, as I envision no down pressure will be needed in a typical sled scenario that just sits on the top and is not captured.

You can make this as complex as you'd like.  The next step is just to make a full CNC.

 

[Stevenscustomguitars]

Looks like a great idea. I've seen someone do this before, possibly on the TDPRI (telecaster) forum.

How do you fix the SBR20 to the 8020?

edit: here's one i remember but there was also one like yours fixed to 8020.http://www.tdpri.com/threads/new-router-sled.709129/

 

[ChiknNutz]

...How do you fix the SBR20 to the 8020?...

If you use double 30-series 8020 rail, that matches the spacing of the SBR20 rail.

 

[Bob D.]

Nice design.  Since it is so big are you going to push it by hand or use a motors/hydraulic/chain drive ...?

Initially just all by hand.  By having fully supported rails & bearings, I thought about attaching a simple horizontal rod so you could just push the carriage along from one side, as I envision no down pressure will be needed in a typical sled scenario that just sits on the top and is not captured.

You can make this as complex as you'd like.  The next step is just to make a full CNC.

In place of the rod why not a cable drive with a hand crank, then you are half way to adding stepper motors. Or use a linear actuator and multiply it's travel with a 3:1 gear drive.