Looking for a block of cast iron please

[Tifa 8572Participant @tifa857287838]

I fancy making a toolpost support for my Chester DB10 to replace the compound.

About 6"x6"x3"

Does anyone have any idea where best to buy this please.

I've looked at online suppliers, but the postage can be sometimes more than the material.

Thanks chaps! (And chapesses!)

[Tifa 8572Participant @tifa857287838]

[John HaineParticipant @johnhaine32865]

**LINK**

Unless you collect it, given the density is constant, the postage will be the same.

[not done it yetParticipant @notdoneityet]

Why cast iron? Most tool posts are steel?

[Frank GorseParticipant @frankgorse]

M machine metals list it,also same size in steel.

Sorry,ignore that,misread size!

Okay,third try,they really do list 150x150mmEdited By Frank Gorse on 16/04/2021 22:18:09

Edited By Frank Gorse on 16/04/2021 22:21:38

[HopperParticipant @hopper]

Steel is not so gawdawful messy to machine too. I made my "gibraltar' style toolpost support/topslide eliminator out of two pieces of 20mm x 75mm flat steel bar welded together. Longer piece for the base and the second "deck" welded on top of that was the same size as the 4-way toolpost sat on top of it. Works a treat. Rigid and does not foul the tailstock.

Edited By Hopper on 17/04/2021 05:31:28

[Ron LadenParticipant @ronladen17547]

If you want to go with cast iron M-machine will cut you 3 inches of 150mm x 150mm at £21.60 per inch so £64.80 plus £10.20 carriage covers up to 30kgs.

[JourneymanParticipant @journeyman]

If you haven't yet a design in mind have a look at my ** Cross-Slide Toolpost ** for the WM250. Fabricated from steel and doesn't use anything quite as big as 6" x 6" x 3" Article is quite lengthy but also covers fitting a QCTP.

John

[Paul MParticipant @paulm98238]

I recently made two tool posts based on the above designs. I used steel as I avoid cast iron unless necessary, due to the mess. A significant improvement in rigidity especially with parting. Well worth doing. Materials from M-machine.

[Howard LewisParticipant @howardlewis46836]

Steel would be better than cast iron; cleaner to machine as well.

Look up Dr_ MJN's thread on how he cracked the cast iron rear toolpost. that he made for his lathe.!

It has had to be reinforced with a steel plate.

When you tighten the clamp screws for the tool, the cast iron is subjected to tension. Cast iron is strong in compression, but not in tension, so it cracks.

Howard

[DC31kParticipant @dc31k]

Posted by Howard Lewis on 17/04/2021 12:16:52:

When you tighten the clamp screws for the tool, the cast iron is subjected to tension.

To quote from the original post "a toolpost support for my Chester DB10 to replace the compound".

Could you please posit a mechanism whereby a toolpost SUPPORT will be subjected to the tensile forces you mention.

I find it of great utility to read all of the words actually written in the original post rather than to omit or imagine some.

[not done it yetParticipant @notdoneityet]

I find it of great utility to read all of the words actually written in the original post rather than to omit or imagine some.

True, but you might say I should not have used my imagination? We all read too quickly, or not deeply enough, at times.

[old martParticipant @oldmart]

I would also go for mild steel, unless you can get some SG cast iron. Cast iron is the messiest stuff to machine as the dust gets everywhere. The SG, (spheroidal graphitic, or ductile iron) is easy to machine not brittle and the swarf is nice, too.

[Nigel Graham 2Participant @nigelgraham2]

I wonder if aluminium alloy would be appropriate here, perhaps with mild-steel facings were appropriate.

However, Tifa asks about suppliers.

College Engineering Supply is one firm that comes to mind, for cast-iron blocks.

[Tony Pratt 1Participant @tonypratt1]

Whether you buy CI or MS the postage will be the killer, not sure where you are in the world but try searching for nearby metal suppliers near to your location.

Tony

[Bernard WrightParticipant @bernardwright25932]

150mm x 150mm x 80mm Cast Iron from College Engineering Supplies will cost you £77.84 inc P&P tax isn't mentioned.

Seems rather a lot

[Howard LewisParticipant @howardlewis46836]

DC31k

I think that you are not referring to the thread which referred to a cast iron toolpost..

My comment did not apply to the SUPPORT, which was added AFTER the cast iron cracked.

One of the earlier pictures in that thread shows the cast iron having cracked in the top corner of the tool slot..

If you think about the component parts.

Tightening the clamp screws, puts the clamp screw into compression. The reaction to this is a force pushing the material above the slot upwards. The corner of the slot concentrates stress (stress raiser ) and the material above is subjected to tensile forces. Which is why it cracked at that point.

When a steel support plate is bolted into place, the support is compressed by the fixings, (Which are in tension ) but the area above the tool slot is then subjected to a bending stress, by virtue of the material around the tappings being forced up wards. This conforms to Newtons laws, about which we were taught in Physics.

I hope that the above clarifies your understanding.

Howard

[JasonBModerator @jasonb]

Howard, it is not a toolpost that teh OP wants to make so no tool clamping screws. It is a replacement for the topslide.

Also while we are at it the Doc did not make the toolpost as you said, it came with his second hand lathe.

This is the sort of thing the OP is talking about

[egaParticipant @ega]

Thanks for the link.

I was quite surprised to learn that the German(?) for toolpost is apparently "toolpost"!

I didn't watch the whole video and don't know how he achieved that beautiful shape – but I would have recessed the four hold-down screws.

[JourneymanParticipant @journeyman]

Bit less machining in this one! Link in post above.

Can be used with either a QCTP as shown or with the original 4-way toolpost.

John

[JasonBModerator @jasonb]

Ega, he did it on his home made CNC

[egaParticipant @ega]

Thanks, Jason!

[IRTParticipant @irt]

I purchased a lump of cast iron from M-Machine last month for the same thing.

I can confirm – yes, it is very messy!

[Tifa 8572Participant @tifa857287838]

Thanks everyone for your replies!

There's a lot of food for thought…looks liks I'll be going back to the drawing board!

Thanks again…it's very much appreciated!

[Howard LewisParticipant @howardlewis46836]

Sorry, misunderstood the OP. From the size of block mentioned, became confused and thought that it was another toolpost to be manufactured.

Howard

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