Help: making a bum shaped impression in bar stools

**artful bodger** · 20th July 2015, 08:01 PM

Hi Eamon.
I have made quite a few chairs that have been carved to better fit the bum. A bit like the old style cast iron tractor seats (that are surprisingly comfortable).
What I did was to get the bit of wood you are going to make it out of, sit on it...then mark with a vertically held pencil around your bum outline.
Once you have done that then you can start to carve away with whatever means you have available (In my opinion, continual sitting and spilt alcohol as a previous poster suggested. might take a bit long).
My first ever chair done this way I used a reasonably big "backgouge" then sandpaper. However later ones I have used an Arbortec attachment on an angle grinder to remove material quicker. Then a gouge/chisels to fine/fair it down more, then sandpaper.
That is using one solid piece of wood for the base.
I have seen a video of the famous chairmaker, "Sam Maloof" who used a bandsaw with some rather precarious looking cutting tecniques to do the rouging out but his seat bases were not a single piece in the video.
However you decide to do it, once you start carving out the comfortable bits you then sit on what you have done and wriggle your bum around a bit to feel where bits feel like they are uncomfortable...and carve away to correct the feel. Then keep sitting,wriggling,adjusting etc untill you are happy with the result. Here is a couple of pics for your perusal.
As a sidenote. Arbortecs can be dangerous, BEWARE!. They will kick back like a chaisaw if used the wrong way. However once you know where the kick back danger parameters are....they will remove a lot of wood really quickly and quite safely.
Good luck.
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**clear out** · 22nd July 2015, 02:59 AM

The main trick to using any disc on an angle grinder is to have the side handle attached and to use it.
Always have the job firmly held down and never hold it with one hand and the grinder in the other.
Sooner or later you will chew up the hand holding the job.
H.

**mitzee** · 22nd July 2015, 03:00 PM

Hi Eamon,

This was something which stumped me as well, I was aware that it is often done using a grinder with a carving blade but that seemed pretty scary to me and I thought it unlikely that I could make two the same. After a bit of tinkering I decided to try mounting a trimmer router in a gimbal type of arrangement which would allow me to cut shallow concave depressions. The idea was to make a bowl shaped depression and then if I could prevent the gimbal from swinging in one direction and move the chair seat a little bit at a time it would be possible to create a concave trough (hope that makes sense). Overlapping the trough with the concave bowl would give me one side of the seat depression that I was after. Doubling this up (one for each cheek if you like) on the seat created a depression which (once sanded) is quite comfortable. It's important to take only small cuts at a time and lower the router accordingly. I just hung the jig from my combo machine table, the length of the arm determines the arc that the router swings through and thus the radius of the cut. Some pics attached
It didn't take too long to do and seemed safer than any other way I could think of.

I saw the utube video of the guy using his tablesaw with quite a clever jig (which was linked in a previous post) and will probably give that a try in the future.

Good luck and keep us updated with which method you choose.

Regards
Bart

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**bendover1** · 22nd July 2015, 05:27 PM

Take a flat piece of wood then have my sister in law sit on it.

**Ozzie** · 23rd July 2015, 08:39 PM

Hi Eamon,
there was a members contribution in a Fine Woodworking magazine a few years ago which cut the "bum" provile using a router mounted on a simple jig which could be adjusted to give the shape with the centre mound.
Maybe worth looking this up as it seemed to be quite simple to set up.

Regards, John

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