Making a 200mm circular recess in board

[Dengue]

I have a 300mm diameter 25mm thick circular base plate for a stand I am making. The base plate is made of radiata pine.

I need to make it heavier for stability, and I am thinking of fitting a 200mm diameter 10mm thick steel plate in the underside, in a circular recess, so that it is flush with the underside.

I do not want any holes or marks on the upper side of the base plate.

Can anyone please advise the best way to do this 200mm diameter 10mm deep recess?

[pal]

If you have a router you could make a trammel or circle jig along these lines.

[Dengue]

Thanks for this pal, looks good, but it will still leave a big island in the centre

[burraboy]

Thanks for this pal, looks good, but it will still leave a big island in the centre

When you've done the first one, do another smaller one. Repeat as necessary.

[BobL]

This jig was Tek screwed to the log but it would be possible to hot glue your workpiece onto a piece of MDF underneath and perch the MDF with the right size hole on a couple of stand offs from the bottom
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Dish11.jpg

Here you can see the Al angle is attached to the router base and is free to act as a router sled that you can move in any direction.
Dish2.jpg

Final result with edge roundover
Dish4.jpg

[Chief Tiff]

Cut out the donut shape with the trammel arrangement; yes this will leave an island initially.

Now you mount the router either on skids or a very wide wooden baseplate, long enough to straddle the recess and rout out the island freehand. Or if the island has been reduced to the minimum you can get with the trammel bar you might have enough room in the recess to temporarily stick on a couple of blocks on the router baseplate.

Bobl and I were answering at the same time I see; he has kindly provided photos.

[Dengue]

Way to go, BobL !! Thanks for this. You too, Chief. Another case of a picture worth a 1,000 words

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[Blackforester]

Find a friend with a lathe. Stick the workpiece to the face plate with double sided tape and turn away.

[woodPixel]

The REAL question for BobL is WHY would you put a circular indent into some random log, in the middle of winter and WHY would you photograph it!

[Handyjack]

woodPixel, I think you will find that is sand in BobL's images. What makes you think it is winter?

[BobL]

The REAL question for BobL is WHY would you put a circular indent into some random log, in the middle of winter and WHY would you photograph it!

I could reinvent the wheel but instead see Post #43 in this thread
Back to milling at last

Make sure you read the "artistic rationale" in post #44

[malb]

I would go with something along the lines of BobL's suggestion and photos. However for stability, you want to make the recess a mm or so deeper than the material you want to place within it to ensure that the outer face of the infill is recessed and the base is supported only around the periphery. If at all possible, I would also increase the recess and infill diameters in order to reduce the width of the contact anulus. You don't need a lot of contact area, and if there is warping etc over time, a lot of contact area may reduce stability over time.