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Myford Super 7 Top Slide Base - Alternatives?

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Hillclimber30/06/2019 08:39:34
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153 forum posts
34 photos
Posted by Chris Trice on 30/06/2019 01:08:23:

I built the Hemingway kit about ten years ago. It's a nice bit of kit BUT I've never had cause to use it and it's languished in a drawer ever since.

Chris, you have a message in your inbox!

Cheers, Colin

Nicholas Hill30/06/2019 13:54:06
25 forum posts
14 photos

Hello again,

My little vibration survey, was basically using the Physics Toolbox App on my smartphone. It rather usefully utilise the phones accelerometers, to show g (9.81m/s) in xyz axis, etc. It also has a pause feature when recording, so by placing it at various points, one can find the unusual vibrations very easily. It also highlighted that by not securing my lathe to the floor, it has a constant ambient vibration, but as it is doesn't vary across the whole lathe, it should be ok. But ideally needs sorting out, in the long term.

Nicholas.

Hillclimber08/10/2019 14:07:00
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153 forum posts
34 photos
Posted by Adrian 2 on 26/06/2019 10:24:20:

I wonder why it has cracked ? Are the thrust pads present and correctly installed in their respective holes? They are handed and easy to fit incorrectly.

Adrian.

Reopening this old thread, I finally realised the significance of Adrian's comment about the thrust pads being handed. Yesterday I was scanning a parts list and found that the right and left pads have different part numbers. Today I was cleaning and adjusting my cross slide.

I had noted that despite my caution in nipping up the pads on the topslide, there were new, uncomfortable marks where why former topslide base casting had broken (like Nicholas's). So I pulled out the pads and sat them on the casting, where they also looked uncomfortable - flipping them around, they looked more naturally poised.

It is difficult to describe the geometry of the respective surfaces, and I have no idea how to tell the pads apart visually. But knowing that they are different, and checking for natural 'poise', I'm hoping this is the solution...

Cheers, Colin

ega08/10/2019 14:50:52
1284 forum posts
108 photos
Posted by Hillclimber on 08/10/2019 14:07:00:
Posted by Adrian 2 on 26/06/2019 10:24:20:

I wonder why it has cracked ? Are the thrust pads present and correctly installed in their respective holes? They are handed and easy to fit incorrectly.

Adrian.

Reopening this old thread, I finally realised the significance of Adrian's comment about the thrust pads being handed. Yesterday I was scanning a parts list and found that the right and left pads have different part numbers. Today I was cleaning and adjusting my cross slide.

I had noted that despite my caution in nipping up the pads on the topslide, there were new, uncomfortable marks where why former topslide base casting had broken (like Nicholas's). So I pulled out the pads and sat them on the casting, where they also looked uncomfortable - flipping them around, they looked more naturally poised.

It is difficult to describe the geometry of the respective surfaces, and I have no idea how to tell the pads apart visually. But knowing that they are different, and checking for natural 'poise', I'm hoping this is the solution...

Cheers, Colin

I have found it possible to tell one from the other by feel. They could be marked in some way. Of course, none of this will be easy if the wrong-way-round pads can't be removed from their bores!

BTW, isn't the Gibraltar toolpost secured in the same way and therefore rotatable, too? (Your earlier post refers).

Michael Gilligan08/10/2019 15:27:29
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14121 forum posts
614 photos

Posted by Hillclimber on 08/10/2019 14:07:00:

[…]

It is difficult to describe the geometry of the respective surfaces, and I have no idea how to tell the pads apart visually. But knowing that they are different, and checking for natural 'poise', I'm hoping this is the solution...

Cheers, Colin

.

I think it’s simply a matter of their axis being offset from the centre of rotation of the topslide.

Can’t check, because I am a lowly 7R user.

MichaelG.

ega08/10/2019 15:37:53
1284 forum posts
108 photos

MichaelG:

You are correct; I assume the reason is to achieve a greater wedging effect.

The design is something of a compromise and I think the "lowly" version has the advantage of better clamping.

Edited By ega on 08/10/2019 15:38:41

Michael Gilligan08/10/2019 15:45:59
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14121 forum posts
614 photos
Posted by ega on 08/10/2019 15:37:53:

You are correct; I assume the reason is to achieve a greater wedging effect.

.

Thanks for the sanity-check

The logic is that if they were diametrically opposed, you could get unpredictable clamping ... but as arranged it is kinematically superior because it is urged to a condition approximating ‘three point’.

MichaelG.

.

Ref. Graham Meek’s thread: https://www.model-engineer.co.uk/forums/postings.asp?th=145209&p=1

Edited By Michael Gilligan on 08/10/2019 15:50:36

ega09/10/2019 11:19:26
1284 forum posts
108 photos

MichaelG:

Thanks for the link which I will pursue. In the meantime, as a patent buff, you may be interested in the three point arrangement of the Tormek work rest which I hope is clear from my photo:

dscn1647.jpg

The wedging action is such that when the black knurled clamp screw is loosened the rest retains its position but is readily removed.

I would accept "urge" to describe the action of the clamp here; in other situations, "bias" might be appropriate.

ega09/10/2019 11:26:06
1284 forum posts
108 photos

PS I notice that Graham Meek offered "bias" as an alternative, too.

I hope he can be persuaded to write up his adaptation.

Michael Gilligan09/10/2019 15:57:10
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14121 forum posts
614 photos
Posted by ega on 09/10/2019 11:19:26:

MichaelG:

Thanks for the link which I will pursue. In the meantime, as a patent buff, you may be interested in the three point arrangement of the Tormek work rest which I hope is clear from my photo:

dscn1647.jpg

The wedging action is such that when the black knurled clamp screw is loosened the rest retains its position but is readily removed.

I would accept "urge" to describe the action of the clamp here; in other situations, "bias" might be appropriate.

.

Thanks for sharing that ^^^ ... it’s neatly done yes

As for urge vs bias ... I have no problem with either

... I was simply revelling in the fact that Gray had increased the richness of the forum’s vocabulary.

MichaelG.

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