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Looking for a block of cast iron please

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Tifa 857216/04/2021 21:41:51
24 forum posts

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!)

John Haine16/04/2021 22:03:17
3826 forum posts
222 photos

**LINK**

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

not done it yet16/04/2021 22:05:27
5853 forum posts
20 photos

Why cast iron? Most tool posts are steel?

Frank Gorse16/04/2021 22:15:51
52 forum posts

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

Hopper17/04/2021 05:30:43
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5427 forum posts
134 photos

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 Laden17/04/2021 06:43:08
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2188 forum posts
437 photos

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.

Journeyman17/04/2021 06:56:34
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953 forum posts
178 photos

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 M17/04/2021 09:32:13
61 forum posts
3 photos

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 Lewis17/04/2021 12:16:52
4738 forum posts
10 photos

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

DC31k17/04/2021 14:20:53
452 forum posts
1 photos
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 yet17/04/2021 14:25:48
5853 forum posts
20 photos

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 mart17/04/2021 14:47:58
2908 forum posts
184 photos

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 217/04/2021 15:51:59
1398 forum posts
20 photos

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 117/04/2021 17:16:32
1503 forum posts
7 photos

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 Wright17/04/2021 19:45:45
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85 forum posts
16 photos

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 Lewis18/04/2021 14:43:52
4738 forum posts
10 photos

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

JasonB18/04/2021 15:21:22
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Moderator
20443 forum posts
2267 photos
1 articles

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

ega18/04/2021 15:39:54
2105 forum posts
175 photos

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.

Journeyman18/04/2021 15:42:46
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953 forum posts
178 photos

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

toolpost.jpg

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

John

JasonB18/04/2021 15:49:28
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20443 forum posts
2267 photos
1 articles

Ega, he did it on his home made CNC

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