# Building a Slab Flattener



## ErikF (Apr 3, 2012)

I'm currently building a large slab flattening setup. Figured I would share a bit about it in the case some of the build techniques could help someone else out.

*Motion*-

The first of these machines I built rode on a "V" shaped track. I turned down a set a wheels that matched the track profile. It worked but it wasn't ideal for taking a decent pass, too much racking force/not very rigid.

This issue has been solved by using linear motion pillow blocks that ride on a shaft. The bearing wrap around the shaft and have a large footprint. They handle a much higher side force and don't rely on weight to stay firmly on the rail. You could flip the machine upside down and all motion would still function smoothly. They're expensive but work well.

*Head Travel-*

Two options…move the slab to the cutter or move the cutter to the slab. Moving the slab to the cutter makes the head assembly simpler and more rigid, but, it's time consuming and leaves room for error and movement. On the first machine I moved the slabs up to the cutter. It was a pain.

This machine has 7" of vertical travel at the head. It is more complicated to build but the slab can remain stationary. Once one side is done, flip it and there should be no need for adjustment to get an even thickness.

The mounting plate for the motor and the spindle moves in a slot with a set of gibs. This allows small adjustments for head alignment and also allows the head to be snugged down during use. The head is raised and lowered using a 1" acme rod that has been turned down- similar to the adjustment screw on a vise.

*Spindle*

Could have used a router or dedicated CNC spindle motor but I wanted to have a wide range of tooling to run. Also didn't want to drop a ton of cash on the spindle. We fitted a R8 spindle to a set of high speed pillow blocks to allow the use of collets as well as a wide range of carbide insert tooling. Anything that you can run on a Bridgeport vertical mill can be run on this setup.

*Speed Control*

To raise and lower the cutter speed there will be a variable frequency drive wired to the motor. This requires a 3phase motor (we are using a 5hp).

Still some odds and ends to finish up before it's done. Should be done this week so I'll give a final update. Feeds are manual.

Video

How do I get the pictures rotated?


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## rwe2156 (May 7, 2014)

Wow that is quite a piece of equipment!!


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## Unknowncraftsman (Jun 23, 2013)

Ya that badass I have no need for one but I like it.


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## hotbyte (Apr 3, 2010)

Cool. Be sure to post video of it in use


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## Nubsnstubs (Aug 30, 2013)

Pretty good job there, Erik. I can't help with the picture rotation, but someone just posted a thread on "Posting Pictures" a couple days ago. You might find something there to help.

You show a fly cutter in one of the pictures, but how are you tightening it to the spindle. Are you going to use a drawbar like most mills use?

I watched the video, and it looked like there was a lot of distance from the end of the collet and the first bearing. That might cause chatter if it's the case. Correct me if I'm wrong. Other than that, It looks like you've got a winner there. I'll be watching for your next report on progress and hopefully see a finished slab.

I thought about doing something like that to video my turnings, but decided it was too much work for making videos that only I will see. ............... Jerry (in Tucson)


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## ErikF (Apr 3, 2012)

> Pretty good job there, Erik. I can t help with the picture rotation, but someone just posted a thread on "Posting Pictures" a couple days ago. You might find something there to help.
> 
> You show a fly cutter in one of the pictures, but how are you tightening it to the spindle. Are you going to use a drawbar like most mills use?
> 
> ...


There is a drawbar to hold the collets and tooling.

One thing still missing is the table. The slabs will rest a few inches bellow the carriage so the cutter won't be sticking out nearly as much as in the video.


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## donwilwol (May 16, 2011)

you need to put that on wheels. The traveling flattener!


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## BillWhite (Jul 23, 2007)

That is some smooooth operator.
Well done.
Bill


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## OSU55 (Dec 14, 2012)

The function of the machine is explained, but it would be interesting to understand the need. How many slabs do you flatten annually? How much $ will be in the machine? Curious about the ROI.


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## Andybb (Sep 30, 2016)

Beefy!!!


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