Converting plans

[Mrben144]

Hello all,
I purchased a book by Harold Hall on tool sharpening. I intend to build the grinding rest and accessories that are provided in the book. They are drawn in metric using metric sized stock. I am wondering if I should redraw the plans using imperial equivalents, bite the bullet and start looking for metric tools or just work to extract conversions (seems like a good way to scrap parts). My machines can work in either system but I would need to find metric endmills and tool holders.

What do you do when you encounter plans in the opposite system?

Thanks.

 

[woodchucker]

Hello all,
I purchased a book by Harold Hall on tool sharpening. I intend to build the grinding rest and accessories that are provided in the book. They are drawn in metric using metric sized stock. I am wondering if I should redraw the plans using imperial equivalents, bite the bullet and start looking for metric tools or just work to extract conversions (seems like a good way to scrap parts). My machines can work in either system but I would need to find metric endmills and tool holders.

What do you do when you encounter plans in the opposite system?

Thanks.

you do what you want. Why would it matter what we think.
This is like a religious arg. on which system to go with.

 

[GeneT45]

I disagree, this is a pragmatic question. If you plan on working in metric in the future, the new tools might be a worthwhile expense, but they probably are not if you generally use imperial, and particularly if your material is best available in imperial dimensions. I'd convert to imperial, probably in CAD just so I can make sure that I'm accounting for all fits and (hopefully) noting all places with critical dimensions. In a lot of cases you can probably still use the metric dimensions, which leaves you only converting a few hole sized and material thicknesses.

You should probably be aware of H.H.'s website as well: http://www.homews.co.uk/page465.html

Good luck!

GsT

 

[mmcmdl]

Not sure what the issue would be here . I don't own any metric tools other than taps and dies and have worked off 1000s of metric prints . Simple to convert metric to imperial . Being a grinder rest , why would it make a difference anyway ?

 

[Mrben144]

I was merely wondering what more experienced people’s approach or advice on the matter was. The grinder rest is just to give an example. It seemed to me like it was a lot more work to a hard conversion. I agree the rest is very simple but I’m hoping to tackle more intricate projects such as model engines.

Thanks for the responses.

 

[francist]

I think you may have just answered your own question -- for simple work the conversion isn't onerous and would be pretty fast. I don't know I'd want to try converting an entire set of drawings for something complicated like an engine. Seems like an opportunity to get really frustrated and tired of the project before you even get started.

FWIW, I purchased the Harold Hall book on grinding too some years ago but have never tried to copy his plans. What I usually end up doing is reading the material, understanding the concept, and then re-applying the entirety to the system I'm most comfortable with and going from there. In a sense, using the books for inspiration more than actual construction documents. That's just me though, I understand others just want a set of prints to work off and nothing more.

-frank

 

[ChazzC]

I design in both metric and inch (I get yelled at if I say "Imperial"), depending on the project. If it's something that is going to modify or be used on one of my metric hardware machines, drawings are in mm. If it's something that doesn't matter, like claps or fixture plates, I design in inches.

Regardless, unless I'm working from plans that require a hole to be metric, I don't use my limited sets of metric drill bits, just use the closest inch/letter/number drill; and if a metric hole is going to be drilled, you don't need a metric drill bit, just a metric reamer.

For counterbores, it doesn't matter if the CB is slightly larger or smaller that the called-out metric diameter.

While I have metric end mills, I bought them because they were good quality, cost less that inch ones and small sizes for special projects are easier to find. The only instance I can think of where a metric end mill is necessary is if you want a perfected rounded slot end to match a metric width, and then you only need it for the end of the slot since you shouldn't be using an on-size end mill to finish the slot.

So unless I'm missing something, you can make just about anything to metric dimensions with having metric tooling. (OK, let the comments pour in)

 

[MikeInOr]

Hello all,
I purchased a book by Harold Hall on tool sharpening. I intend to build the grinding rest and accessories that are provided in the book. They are drawn in metric using metric sized stock. I am wondering if I should redraw the plans using imperial equivalents, bite the bullet and start looking for metric tools or just work to extract conversions (seems like a good way to scrap parts). My machines can work in either system but I would need to find metric endmills and tool holders.

What do you do when you encounter plans in the opposite system?

Thanks.

I have traditionally kept my shop clean with all old American machines built around English measurements. I bought a couple really nice European machines that needed some refurb. I feel like I am ordering new metric tooling or fasters every other day. I HATE IT! BUT I also see it as inevitable if you spend any time in this hobby, so you might as well start now.

If you have Imperial machines with Imperial scales and no DRO that can be switched to metric with a button... I would consider purchasing a DRO with a metric setting (pretty much all of them today).

Just my 2 pennies.

 

[Flyinfool]

All of my machines are inch, most of my hobbies everything is metric.
I almost never have drawing supplied to work from so I am designing most of what I make. Most parts I make end up with a mix of inch and metric. I use inch where I can and use metric where there is a metric mating part.
I have been doing both systems for so long that I am completely comfortable with both systems and have no issues converting back and forth. the only way to learn it is to use it.

 

[RJSakowski]

With few exceptions,it makes no difference whether you use inch or metric tooling. There is an inconvenience in calculating offsets but this relatively minor. Rather than following a blueprint blindly, I will evaluate it to determine what dimensions can be modified to better suit stock and tooling on hand.

When designing, I tend to use inch dimensions because stock and tooling is more readily available. I will dual dimension in cases where I know I will need to use metric dimension when machining.