Some help on how to get this piece finsihed

[sucramuk]

Hi all

I've thought I'd managed to do the hard bit on building the vacuum pump, making the bags and the forms but I'm a bit stumped on how to trim my piece to finish size.

I need to trim the downturns of the piece so they are all flush with each and also the front edge. The max I would be trimming off would be around 5mm.

I tried to trim the downturns with the piece still on the form and using a flush bit on the router table, tear outs.

Tried to trim front with table saw, but I guess the bend is not 100% true causing the 2 cuts to not line up.

I was now thinking of making a high sided fence for the table saw and running the flat of the piece on it ( have seen on the net something similar with a zero clearance base) for trimming the downturns.

For the front trimming, again high sided but feeding the piece following the contour of the shape (if that makes sense)

Anyone have some more suitable suggestions, or guidance, I really need to start making some!!

TIA

 

[RobinBHM]

I think the most consistent way would be to make a large C shaped sled which is longer than the part so you could clamp front and back.

 

[woodbrains]

Hello,

I think you are right to trim them on the form, but a flush trim bit might not be best. I would use a slot cutter in the router, perhaps 1.5 mm kerf and cut it that way, referencing off the flat side of the form. Even if the diameter of the slot cutter is not big enough to cut all the way, (i don't know how thick your laminations are) it will cut through more than enough to leave a bit to cut through with a hand saw and a bit of a plane to clean up. Likely your lams will not be too thick and the cutter will slice the waste off fine. I have done this many times with great success. There are large diameter ones available and extra long arbours as well, Wealden router cutters sell them, but you are not in Britain so might have to do some research, if standard bits will not suffice.

Mike.

 

[worn thumbs]

Mark the trim line with a scribing block or similar.Cramp the central flat section to a bench and use a hand plane to remove the surplus,it should be safer and more accurate.

 

[sunnybob]

glue it down and use a router mounted on a sled.

 

[sucramuk]

Thanks for the replies.

Some I get the jist of some I don't.

I can't seem to picture how woodbrains has described what to do, sorry for being dumb!

 

[woodbrains]

Thanks for the replies.

Some I get the jist of some I don't.

I can't seem to picture how woodbrains has described what to do, sorry for being dumb!

Hello,

A slot cutter is in essence a tiny circular saw, but it cuts parallel to the router base. Use it to slice off a small amount of material, using the bottom of the form to ride the router base on. I'll try and do a drawing to clarify. The method is pretty widely used for that task. Robert Ingham, for example shows it being done in his book, Cutting Edge Cabinetmaking.

Mike.

 

[sucramuk]

Hi

So something like the attached?

Use a bearing on it, as the arbour is quite long I can space the bearing accordingly.

Use a bearing same cutting width as the cutter? If they exiist, to run of form?

 

[woodbrains]

Hello,

Yes, that is exactly it.

On your job, you could use the router fence to control the depth of cut. You can use the bearing, as long as it doesn't mean you cut too deeply in one pass. If your laminations are thick, then use 2 or 3 sizes of bearing to make the cut in multiple passes. Or use successive passes with varying settings of the fence.

Mike.

 

[sucramuk]

Well guys thanks for your advice and input, I've finally made the piece with the making of various jigs etc and taking on advise from the forum.

I tried it today, picture attached it worked well enough.

However I needed to really test the strength of the hanger, so decided to put more weight / force on the front edge. I was expecting to break the back wall piece out from the curved form, that didn't happen.

The screws in the wall plate of the french bracket where pulled from wall and I even managed to bend them. These were in a solid wall , correct plug size etc.

I guess the force of leverage etc is causing this, would the revised plan for the back wall piece alleviate some of this leverage issue?

Suggestions please, I really dont want to see bolt heads in the face side of the wall plate.

Many thanks