Need something milling

[grim_d]

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I can cut to a precise tolerance of plus or minus 1.0000" all day long, soft or hard, toolpost pin or no. If you need more precision in your tolerance, for a little extra cash I can do +/- 1.00000" for you.

Pfft, even I can do plus/minus one inch.

 

[pressbrake1]

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May I make a few observations?

The 15 degree pin offset seems a little bizarre given that the post indexes at 9 degrees. This effectively means you have a 3 (or 6) degree difference at the tool. Were it 30 degrees, it would have some logic to it.

Presumably one of the 15 degree holes is synchronised to/aligned with one of the 9 degree positions. It's probably important that on initial set up of the post that you choose the correct one.

When you pull the pin from the top, do you need to loosen the main securing nut to adjust the angle? If so, then a low-and-wide-T-nut carrier that Brad wants to make would also have to be secured against sliding in its slot to assure repeatability.

A single pin will not assure repeatability anyway as the post could pivot on the pin, taking up any slop in the central securing bolt hole.

If you are going to worry over the dowel pin size, you also need to assure yourself of the tolerance to which both the 5.6mm hole in the toolpost itself is formed and the new hole in the securing-T-nut. At best, the person making it will buy a 'standard' 5.6mm reamer.

I can cut to a precise tolerance of plus or minus 1.0000" all day long, soft or hard, toolpost pin or no. If you need more precision in your tolerance, for a little extra cash I can do +/- 1.00000" for you.

Being able to work +/- 1 inch makes you rough in my book

 

[pressbrake1]

Pfft, even I can do plus/minus one inch.

I think the tolerance he’s claiming in the 1/100000 realm would take dead centre grinding just to achieve that roundness.
.000015 being achievable roundness

 

[Brad93]

Would a 7/32 dowel not be close enough to 5.6mm for this purpose?
https://www.boneham.co.uk/dowel-pin...al-3-inch-solid-dowel-pin-to-bs1804-limits-dp


Edit

LOL looks like @Agroshield thought the same

Looks like 7/32” would work. I’m terrible mixing inches and metric.

 

[Agroshield]

I think the tolerance he’s claiming in the 1/100000 realm would take dead centre grinding just to achieve that roundness. .000015 being achievable roundness

No, no unrealistic claims at all. The post on which I was commenting said, "harder materials are easier to machine to precise tolerances". I simply gave an example of a precise tolerance.

I agree that it was a very, very loose tolerance (think burning gear after 15 pints) but you cannot say it was not precise.

One can sensibly speak of precise dimensions. We discuss tight tolerances. But when someone talks of precise tolerances, one wonders if they understand the terms which they are utilising.

 

[Paul in Wiltshire]

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The 15 degree pin offset seems a little bizarre given that the post indexes at 9 degrees. This effectively means you have a 3 (or 6) degree difference at the tool. Were it 30 degrees, it would have some logic to it.

I think there is some misunderstanding. The tool post has a reference pin hole at an arbitrary position, call it 0 degrees. Set your post up to present the tool perpendicular to the axis, then drill the dowel pin hole in whatever the post is mounted to to provide repeatability. (Accepting a compound won’t satisfy that). In the toolpost there is a second reference pin hole 195 degrees from the first, that’s the 15 degree offset. As you observe, with 9 degrees between the 40 positions that represents an offset of 3 or 6 degrees from the first reference hole. So reference hole one allows you to index between 0,9,18,27,36,45,54,63,72,81,90 etc. Switch to reference hole 2 and you can get 3,12,21,30,39,48,57,66,75,84 etc. So you can get 30 if that’s what you want. All moot if you intend to move your compound around.

As for the semantics of ‘precise tolerances’ I think you know what I mean. ‘One wonders if they understand the terms which they are utilising’, happy to have a qualifications ******* match if you’d like?

 

[Agroshield]

...Set your post up to present the tool perpendicular to the axis, then drill the dowel pin hole in whatever the post is mounted to to provide repeatability.

Thanks for that. As I understood it, Brad wanted the plate making with the hole already formed. From what you have said, this plan may not work. As you say, the hole needs to be made insitu, on the machine, when the post is dialled in.

 

[pressbrake1]

I think there is some misunderstanding. The tool post has a reference pin hole at an arbitrary position, call it 0 degrees. Set your post up to present the tool perpendicular to the axis, then drill the dowel pin hole in whatever the post is mounted to to provide repeatability. (Accepting a compound won’t satisfy that). In the toolpost there is a second reference pin hole 195 degrees from the first, that’s the 15 degree offset. As you observe, with 9 degrees between the 40 positions that represents an offset of 3 or 6 degrees from the first reference hole. So reference hole one allows you to index between 0,9,18,27,36,45,54,63,72,81,90 etc. Switch to reference hole 2 and you can get 3,12,21,30,39,48,57,66,75,84 etc. So you can get 30 if that’s what you want. All moot if you intend to move your compound around.

As for the semantics of ‘precise tolerances’ I think you know what I mean. ‘One wonders if they understand the terms which they are utilising’, happy to have a qualifications ******* match if you’d like?

I think only one person was slightly ribbed for stated tolerance and it wasn’t you

 

[grim_d]

One can sensibly speak of precise dimensions. We discuss tight tolerances. But when someone talks of precise tolerances, one wonders if they understand the terms which they are utilising.

I don't see why you can't have "precise tolerances"?

If I have to make 5 parts at 1" +/- .005" and I make 5 parts at 1.001" then they are all precisely within tolerance?

 

[Seadog]

It can't be precise if it has a tolerance.

 

[mtt.tr]

Its all relative, even standards vary nation to nation.

Its a tee nut Christ worse case use an angle grinder and a file, its only a distribute the clamping and stop a chunk of the t slot being broken.

 

[Agroshield]

Just seen elsewhere the type of bolt Schaublin use for holding their toolpost. The most salient feature is that the part directly under the stud is relieved (so it bears on four pads at the 'corners'). If you arrange the pads so they are directly under the ring of the Multifix post, then the wings of the compound only see compression stress and no possible bending.

 

[grim_d]

It can't be precise if it has a tolerance.

Not true, tolerance relates to accuracy, precision measures repeatability.

If you are shooting at a target with a rifle, let's say aiming for the bullseye, and you shoot 5 shots that all end up 1" above the bullseye then your accuracy is off but the shots are precise.

Precision measuring equipment is precise because it gives you repeatable measurements, even an inaccurate micrometer would be precise.

 

[Seadog]

One of the meanings of precise is "exact." Something cannot be exact if it has a range of variance. I do love semantics

 

[grim_d]

One of the meanings of precise is "exact." Something cannot be exact if it has a range of variance. I do love semantics

Exact, exhibiting or marked by strict, particular, and complete accordance with fact or a standard

A tolerance would be the standard by which the part would have to strictly adhere.



But seriously, if all 5 parts were 1.001" then there's no range of variance so they are all precisely within tolerance.