Thread: small circular cut

turned on a lathe?

I don t think so I know that these blocks are cut first and then the hole is made later on

They could be made on a router table with a circular jigs to restrict the movement of the inverted disc.
You would want to be very careful holding the disc - I'd be doing it with a length of wood double sided taped to the back of the disc.
Starting would be tricky but I would drill a flat bottomed hole in the wood to the required depth.

It would also be possible to do it with the router on top by mounting the disc into a jig to hold it still. That would be a lot safer.

BobL is spot on. That how I'd do it.

Make a jig. Four segments of timber to hold the work piece (3 if you want to be minimalist)*, then plonk a template on top. The template has the pre-drilled hole in it. The template is located on the holding segments below with dowels. The dowels can protrude up from the segments into small locating holes in the template.

Pop the piece in the holder, pop on the template, whizz around the hole with a top bearing router bit, voila.

120 pieces done an hour.

* I chose 4 as once they are fixed down, just draw a line diagonally from each, this gives the centre for the templates big hole to be drilled.

Ahhh I spent quite a bit of time last night thinking about it and that what i came up with as well.

I understand the concept now it will just be a matter of doing it.

Thx guys for your help i ll go get a top bearing router bit today and try that

jon

Originally Posted by ian

turned on a lathe?

I think this too.

Originally Posted by Evanism

BobL is spot on. That how I'd do it.

Make a jig. Four segments of timber to hold the work piece (3 if you want to be minimalist)*, then plonk a template on top. The template has the pre-drilled hole in it. The template is located on the holding segments below with dowels. The dowels can protrude up from the segments into small locating holes in the template.

Pop the piece in the holder, pop on the template, whizz around the hole with a top bearing router bit, voila.

120 pieces done an hour.

* I chose 4 as once they are fixed down, just draw a line diagonally from each, this gives the centre for the templates big hole to be drilled.

that might cut the hole, but how do you get the block round in the first place?

Safest would seem to be on a lathe using an expanding chuck in the hole -- but probably fastest to start by turning a long square section into a "log", then almost part (or saw) off each block.
there's lots of ways to hold a circular object while you turn the depression.

If you have a look at some of Template Tom's work, I'd be incline to go with the use of a router to do the whole lot.

i been experimenting a lot with these blocks that I use on an everyday basic in my job and tried most of the options :

router : doesn't matter the bit it leaves lots of tear out
jigsaw : jig or not it is never perfectly round or even
lathe : never tried i do not have one but i guess it would be pretty lovely
table saw : with a jig the best result i got so far, also the quickest.

for the inside hole i am almost 100% sure a router has been used ( according to the similar small tear out that i would normally get using a router for the main block )

i will post a picture of what i got as soon as i find a top bearing flush bit for my 1/4".

Saw this exact thing yesterday. Turned on a lathe.

The outside could be easily cut on a bandsaw using a jig, then cleaned up on a disc sander also using a jig (or freehand). Then a router w/ template for the hole in the middle.

Alternatively, a waste block with a tenon could be glued to the blank piece of timber, then it could be rounded on the lathe, followed by the inside hole also on the lathe. If hot melt glue is used to attach the waste block, it can be removed with metho and a little patience.

the object looks like a tea light holder

I'm still thinking lathe -- fastest, safest, and can come off the lathe fully finished -- all vital considerations if you're making them for sale

Yep, I agree with Ian, this is a trivial job on a lathe, but if you don't have one, that's not much help.

The quickest method of all to make the 75mm central depression would be to use a 3" Forstner or sawtooth bit. They will give you a flat bottomed hole, but the point will leave a small divot in the centre, which you may or may not be able to tolerate. A 3" bit is a pretty substantial chunk of metal, & you need a decent drill-press to swing it. You would also need to clamp the workpiece down securely!

Cheers,

+1 Definitely on a lathe.

I think it would be quite difficult to cut that shape with a router and have a good finish on the end grain.