[Project 4] Sine plate

[Lee Jones 6Participant @leejones6]

[Lee Jones 6Participant @leejones6]

This, like many of my projects I suspect, is a spin-off from [Project 3] Dickson T1 Tool Holder

This option was chosen because it seems the most sustainable i.e. it will be used on other subsequent projects.

I have, in my possession 2 x 32mm thick steel plates taken my old welding table. They're 90kg each!

I took a section from one of them using a 4" angle grinder!

It's around 400mm x 250mm (and weighs 20kg).

The first task will be to square it up.

However, a couple of issues are impeding;

• It recently transpired that my facemill has shoddy inserts
  • Currently waiting on new ones from Arc
• I am lacking low-profile table clamps
  • [Project 5] I think! Sheesh, how far does the rabbit hole go?

[SteviegtrParticipant @steviegtr]

You sound like me. Every time I decide to do something. I need something else to make it possible. Never ending.

Steve.

[JasonBModerator @jasonb]

Put a few counterbored holes in it to hold it down with some short cap heads.

At that size you are going to need a big stack of gauge blocks to get 45deg!

[Martin ConnellyParticipant @martinconnelly55370]

Welcome to the world of sub-sub-sub projects. It may be worth thinking about annealing such a large plate before you start skimming the face and finding it curling up. Think large bonfire and leaving it to cool in the ashes. With such a large plate it should be possible to have extra clamps around the edge and remove and replace them as necessary to leave a clear path for the tool to pass while still keeping it securely clamped. Change clamp positions when the tool has gone past the end and before the next cutting pass. I would also recommend using packing under the plate where the clamps are before skimming the first surface to avoid any rocking of the face against the table. Nothing major, just needs to be strips of something with consistent thickness such as a bit of 16swg plate.

Martin C

[Lee Jones 6Participant @leejones6]

I don't own any gauge blocks yet!

Although I suppose the larger the sine plate, the less accurate the stack needs to be?

Perhaps at this size the stack could even be machinable?

[Lee Jones 6Participant @leejones6]

Posted by Martin Connelly on 24/05/2020 19:52:37:

Welcome to the world of sub-sub-sub projects. It may be worth thinking about annealing such a large plate before you start skimming the face and finding it curling up. Think large bonfire and leaving it to cool in the ashes. With such a large plate it should be possible to have extra clamps around the edge and remove and replace them as necessary to leave a clear path for the tool to pass while still keeping it securely clamped. Change clamp positions when the tool has gone past the end and before the next cutting pass. I would also recommend using packing under the plate where the clamps are before skimming the first surface to avoid any rocking of the face against the table. Nothing major, just needs to be strips of something with consistent thickness such as a bit of 16swg plate.

Martin C

Re-clamping was certainly an option, I need an excuse to make LP ones. 😀

Will I have to re-temper after?

[JasonBModerator @jasonb]

If you are not going to be setting it accurately you may as well just make an angle table and rough set with your digi box then clock it to final position. Add a jacking screw for easy setting, this sort of thing

[Martin ConnellyParticipant @martinconnelly55370]

No re-tempering, you are making sure it is soft and stress free before cutting it. It may already be stress free but for something this large better safe than sorry. Just think of all the little spots on top of a weld table that have had localised heat treatment that may have created stress.

Martin C

[Lee Jones 6Participant @leejones6]

Posted by JasonB on 24/05/2020 20:15:14:

If you are not going to be setting it accurately you may as well just make an angle table and rough set with your digi box then clock it to final position. Add a jacking screw for easy setting, this sort of thing

In my mind, that's pretty much what I'm making, with the added bonus of being able to set out precisely if required.

[Lee Jones 6Participant @leejones6]

Posted by Martin Connelly on 24/05/2020 20:27:13:

No re-tempering, you are making sure it is soft and stress free before cutting it. It may already be stress free but for something this large better safe than sorry. Just think of all the little spots on top of a weld table that have had localised heat treatment that may have created stress.

Martin C

Got you. Makes sense.

So long as the entire structure won't all become too soft.

[Martin ConnellyParticipant @martinconnelly55370]

Soft here is a relative term. It will never be as soft as lead but it won't be as hard as tool steel. It will hopefully be like a nice even piece of mild steel.

Martin C

[David George 1Participant @davidgeorge1]

we had a large sine table at work about 3ft by 4ft and the top plate was 3 inch thick. we made standard size bars to go under the plate to suit all the jobs we did from 5 deg to 45 deg. It was made of ground plate P20 I think, and was covered by a pattern of tapped holes to clamp jobs on for milling. You had to use a jib crane to lift the top plate to use it but it did loads of jobs for tool making moulds etc.

David

[Lee Jones 6Participant @leejones6]

For you Martin:

[SteviegtrParticipant @steviegtr]

Bet your neighbours think you are nuts. Trying to burn a block of steel.

Steve.

[Lee Jones 6Participant @leejones6]

Think I'm going to take up blacksmithery!

Just going to sit here with my whisky until it becomes malleable!

[Martin ConnellyParticipant @martinconnelly55370]

Tell the neighbours it's engineering, see if they believe you

Martin C

[Lee Jones 6Participant @leejones6]

And I quote, "that's it, he's finally lost his last marble".

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