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Mr Fixit
01-22-2017, 06:10 PM
Hello Group,

The project is a Stirling engine, the Coffee Cup model, and I could only find it available free in metric on line.
I have the set of model plans in metric but do not have metric taps, hardware or measuring tools, so I'd like know, is it possible to take and convert a few dimensions to inch for the whole plan, and it will get me in the direction I need, or are there equivalent inch to mm that are often used that can be plugged in. Example 3mm= .1181 which is just under ⅛ for a standard size, 1mm=.0394 which for sheelmetal is 20ga down sized 19ga oversized which the project does call for, 20ga I can work with as I've got some.
I know metric is easy, but I'm old school and for a first small scale engine I'd like to work in inches.

PS. This is a challenge project between myself and a buddy with about the same skill level and if we can do the inch thing that's the best. We want to see how each other's engine turns out and will they run!!
The design is by J Ridder..

OK I'm ready for the sparks to fly.

TX
Mr fixit for the family
Chris. :)

Stepside
01-22-2017, 06:27 PM
Chris

If this were my project, I would print out a copy and convert each and every dimension to the decimal inch equivalent and write it on the drawing next to the mm dimensions. This would give you a place to see what number sized screws are close as well what tubing sizes are close. With a little screwing around with numbers/sizes ect you should get close. Print a new copy and black out the original dimensions and replace with your adjusted sizes. Work from this sheet.

Pete

Mr Fixit
01-22-2017, 06:36 PM
Hi Pete,

I've done just that on the numbers part of conevertin to inch, so now I'm on to the finding a close inch match.
I just wanted to put this question to those here much smarter than I.
Maybe come out of it with some really cool information too!

Thanks for the idea.
PS. It sure took a while!

TX
Mr fixit for the family
Chris. :)

MattiJ
01-22-2017, 07:03 PM
Just a sidenote, metric 20 mm pipe doesn't have 25 mm hole and the OD of 10 mm thread is not 16 mm ;)

aluminium sheet gauge, steel gauge, various wire gauges, drill gauge, pipe threads. I'm going nuts trying to figure out what is what. And I have old inch based lathe with fine thread BSW allen head fasteners :rolleyes:
My workflow with inches is pretty much like this:
https://www.youtube.com/watch?v=EUpwa0je6_Y

J Tiers
01-22-2017, 07:14 PM
Conversion is easy.

Converting to standardized materials and fasteners is harder.

So, the best idea is to convert dimensions, but keep metric for fasteners, because they are often inappropriate when shifted to the other system, either way. (If you do not have the taps, and don't want them, OK, convert, but things may or may not work out easily and cleanly.)

That lets you use your measuring tools in a simple way, and still keep the look the same. Of course, most likely you can use a caliper for nearly all the dimensions, and any digital readout caliper, as well as many dial calipers, will read both. So that is easy. For things that need a mic, convert.

Dimensions are just dimensions, so 0.118 is just a number to cut to... it need not be considered as to whether it was metric or whatever.

If you prefer, yu can convert everything, but do final checks with the metric setting on the calipers, as a check to avoid issues of scrambled conversions.

Metric fasteners are pretty available, so other than the taps, not hard to deal with.

loose nut
01-22-2017, 07:18 PM
Just a sidenote, metric 20 mm pipe doesn't have 25 mm hole and the OD of 10 mm thread is not 16 mm ;)

aluminium sheet gauge, steel gauge, various wire gauges, drill gauge, pipe threads. I'm going nuts trying to figure out what is what. And I have old inch based lathe with fine thread BSW allen head fasteners :rolleyes:
My workflow with inches is pretty much like this:
https://www.youtube.com/watch?v=EUpwa0je6_Y

No one mentioned 20mm pipe or the OD of 10mm pipe. Esplain please.

Mr. Fixit, wouldn't it be easier to just find an Imperial DIM. project.

gellfex
01-22-2017, 07:45 PM
Why convert at all? Just use a digital caliper and work in metric. If you don't want to use metric fasteners it's easy to substitute 4-40 for 3mm, 8-32 for 4mm, 10-32 for 5mm etc. I had to work all metric for are some projects going overseas and had to get a full assortment of metric fasteners and taps.

If the plans are CAD files rescale them in inches.

RB211
01-22-2017, 07:57 PM
Yet another benefit of a decent DRO system

J Tiers
01-22-2017, 07:58 PM
Why convert at all? Just use a digital caliper and work in metric. ....

The issue is really with the machines, the dials are probably in inch, so you either convert, or do a lot of mental gyration to determine the remaining amount to show on the dial for the next cut, etc.

Easy to determine what to do when the dim is 3.246 inch and the dials are inch. Not so easy when you have 82.44 mm and inch dials.

RB211
01-22-2017, 08:02 PM
The issue is really with the machines, the dials are probably in inch, so you either convert, or do a lot of mental gyration to determine the remaining amount to show on the dial for the next cut, etc.

Easy to determine what to do when the dim is 3.246 inch and the dials are inch. Not so easy when you have 82.44 mm and inch dials.
You still use those silly dials?

Mr Fixit
01-22-2017, 08:52 PM
Absolutely RB2ll !

Loose nut, I've tried to find a imperial set of plans but poor designs are the norm, not had good luck. The design I have does use 100mm OD tubing for the hot cold chambers which I found 4" OD clear acrylic that I will size the project around.

TX
Mr fixit for the family
Chris. :)

Jim Williams
01-22-2017, 08:59 PM
Just go ahead and use metric. Use an electronic caliper and switch to metric. I am going to be 86 years old in less than two weeks and use both systems. I have used metric so long that I think and visualize in it OK. Just think of one millimeter as about forty thousands, twenty five millimeter close to an inch, one hundred millimeter close to four inches, and one thousand millimeter as a few inches more than a yard. The few metric taps you will need will not cost enough to worry about. Easy enough to adjust to materials that are on hand or easily obtained.

Jim

elf
01-22-2017, 09:03 PM
I would guess the cost of a couple of metric taps would be less than the cost of the plans. It's pretty hard to buy metric drills for metric taps in the US, but there are imperial drills that are close enough.

If you insist on changing everything to imperial, then you should completely redo all of the plans in imperial.

3jaw
01-22-2017, 10:02 PM
The issue is really with the machines, the dials are probably in inch, so you either convert, or do a lot of mental gyration to determine the remaining amount to show on the dial for the next cut, etc.

Easy to determine what to do when the dim is 3.246 inch and the dials are inch. Not so easy when you have 82.44 mm and inch dials.

I work with metric dimensions every day on ancient inch based machinery and there is nothing hard about converting 82.44 mm into 3.2456 inches. If your worried about the four place decimal on the dial then look at the tolerance and see if it falls within a three place dimension, make the part and get on with life.

Mcgyver
01-22-2017, 10:52 PM
agreed. The gnarly bit is materials, depending on what you are building. If everything thing is machined, its not an issue, but obviously lots of projects involve using material of nominal sizes which means you may have to make adjustments to assemblies. I would just redraw it to standard imperial sizes.

J Tiers
01-23-2017, 12:27 AM
I work with metric dimensions every day on ancient inch based machinery and there is nothing hard about converting 82.44 mm into 3.2456 inches. If your worried about the four place decimal on the dial then look at the tolerance and see if it falls within a three place dimension, make the part and get on with life.

Wow... did YOU ever miss the point..... miles away, my friend.

The point was that no matter if you use a metric caliper, you need to convert dims to inches and write them down, or you will have to do mental arithmetic on the fly to convert in your head to see where you are and where you need to go. The metric caliper is good just to keep a sanity check on the conversions, so you know where you are relative to the print dims, and have not done anything silly with the arithmetic.

I often DO just do the conversion, because I have no trouble with either metric or inch, know many dims in both, or can estimate, and I have measuring tools for both, at least up to 100mm for mics. But the dials are inch, so I have to do some converting usually.

Paul Alciatore
01-23-2017, 01:11 AM
I'm not sure I understand what you want. It seems that you have already converted the metric dimensions to inches. That, undoubtedly produces a bunch of unfamiliar three (or four) decimal place numbers. You can just use them.

If you want to translate to the nearest inch fractions, what I do is multiply an inch decimal dimension by 64 to get the closest 64th of an inch. So, 10mm = 0.3937" and 0.3937" X 64 = 25.20. So 10mm becomes 25/64" with a little rounding. If you don't like 64ths you can multiply by 32 or 16 or 8 or even 4 to get 32nds, 16ths, 8ths, or 4ths.

For screws, I would translate to the closest inch size but in a fine thread. Metric threads tend to be finer than UNCs. M6 is 6mm in diameter: 6mm = 0.326". 0.326" X 64 gives you 15/64" and the closest inch screw size is 1/4" so I would use 1/4-28. If the fine thread is not actually needed, you could use 1/4-20.

For better or worse, you are going to have to apply some intelligence with this process. There will be places where rounding to some inch dimension will present problems and some real design work will be needed. It would probably be best to do a CAD drawing. I would use one set of layers for the metric original and a second set for the inch conversions. That way you can turn layers on or off depending on the feature you are currently working on.

The alternate would be to work to the original metric dimensions. That should not be too difficult. For instance, a part designed to be made from 25mm stock can easily be made from 1" stock with a bit more being removed. And you can easily buy metric fasteners, even here in the good old, stuck in the inch world, US. If your local stores do not stock them, try McMaster-Carr.

J Tiers
01-23-2017, 01:34 AM
I would not fool with converting to standard inch dims. Too much like a redesign of the whole thing, with hassles and extra work.

Just take the conversions as they come, so you get the same size parts as you are supposed to. If you need a little larger material, so be it, that's what machine tools are for. it does not matter if it comes to an even number of thou, 0.117 inch is as good as 0.125, just a number to hit.

An exception might be a piston rod.... if it goes through a gland. Then you can probably get inch size ground and polished rod, but may not have as ready access to metric sizes, so it is worth converting to the nearest size unless you can grind and polish your own turned rod/ McMaster should have most metric sizes though.

MattiJ
01-23-2017, 03:46 AM
No one mentioned 20mm pipe or the OD of 10mm pipe. Esplain please.


It was reference to the funky nominal pipe sizing. If you buy 1" pipe from hardware store it has a 1.1" hole and 1.3" inch outer diameter.
And the same with goddammit pipe threads, 1/4" BSPT thread has diameter a bit over 1/2" :mad:

You cant avoid those even here in metric Europe, BSP pipe thread with 55-degree flanks is the official standard on lots of things. To add confusion some NPT/BSP or NPS/BSPP fitting are close enough to mate but not properly.

RB211
01-23-2017, 04:34 AM
I push the inch/mm button on the DRO. Yes, you could use those silly dials, do the math, etc. Those dials do not represent actual table movement, rather what the table should move. Is your machine old and a little clapped out like my Bridgeport? The DRO fixes those issues for what I do. I don't like doing math in my head, and I REALLY do not like throwing parts in the scrap bin.
If your brain is wired for doing this with dials, you have my respect.

Georgineer
01-23-2017, 05:31 AM
What Paul A. said.

George

MichaelP
01-23-2017, 08:12 AM
I have the set of model plans in metric but do not have metric taps...
This guy converted hardware to SAE and says he can send the converted drawing to anyone who is interested: https://www.youtube.com/watch?v=FpnVE_tSXDg Just read the introduction to his video.

Please don't forget to document your progress and post it on this forum. Good luck!

loose nut
01-23-2017, 09:38 AM
Absolutely RB2ll !

Loose nut, I've tried to find a imperial set of plans but poor designs are the norm, not had good luck. The design I have does use 100mm OD tubing for the hot cold chambers which I found 4" OD clear acrylic that I will size the project around.

TX
Mr fixit for the family
Chris. :)



This web page, right side, has a metric to imperial (as close as possible) conversion chart for threads, so that should take care of that part of your problem.

http://www.connectionserviceco.com/metric-conversion-tables/

As far as materials you have no choice but to use the closest available size, which you are doing, unless you want to order stuff from Europe.

There are thousands of plans available but most are no on the web. HMS magazine has many sets of plans some of which are beginner's level. Older Model Engineer Magazine have lots of great plans at all levels and they can be pick up relatively cheap. They also sell plans in book form (reprints from the mag). Some reprints are available on their website.

http://www.model-engineer.co.uk/

Try this online magazine, they have lots of free plans, most are fairly simple but not all but most are metric. Worth looking at even if you don't build any.

http://modelengineeringwebsite.com/Index.html

Here are a couple of good sites that sell Model Engineering books, some are model plans some are theory. Books are on Amazon and ebay also.

http://www.teepublishing.co.uk/books/hot-air-engines/

http://www.crowood.com/category.asp?cat=27&class=Model-Making-and-Model-Engineering

Your best option is to join a Model Engineering club and get local help. There is a Portland Model Engineering Club.

http://users.easystreet.com/depmco/pme/

Stepside
01-23-2017, 10:43 AM
Chris

If you have a dual mode caliper the conversions are easy. Set to metric mode and open to the dimension you wish to convert. Switch to inch mode and you have your answer. This will get you all the as drawn size dimensions. Your next task is to find the inch sized materials that are closest in size and available. The power output of one of a Stirling engine is tiny if you are building one that runs off the heat of a cup of hot water. Your challenge is not the metric/inch conversion as much as the quality of fit and finish of the parts.

Pete

cameron
01-23-2017, 10:44 AM
It was reference to the funky nominal pipe sizing. If you buy 1" pipe from hardware store it has a 1.1" hole and 1.3" inch outer diameter.
And the same with goddammit pipe threads, 1/4" BSPT thread has diameter a bit over 1/2" :mad:

You cant avoid those even here in metric Europe, BSP pipe thread with 55-degree flanks is the official standard on lots of things. To add confusion some NPT/BSP or NPS/BSPP fitting are close enough to mate but not properly.

There are very good reasons for the actual sizes of piping being what they are. A little study of the history would reveal them to you.

But what the hell does it matter what the actual sizes are? They are not a mystery, there are tables of sizes all over the place. Just deal with it and stop whining about it.

Not everything has to fit into a metric sized box. You'll be wanting your bloody vegetables grown to standard metric weights and sizes next.

SGW
01-23-2017, 11:10 AM
Converting thread sizes is not a big deal. PM me your e-mail address and I'll send you a table I made up, years ago, that lists inch and metric threads sorted by pitch and sorted by diameter. It's very easy to see what inch thread is closest to a metric thread, or vise-versa.

As far as dimensions of parts goes: some dimensions matter more than others. Two parts that fit together have to fit together. The size of the baseplate, on the other hand, could probably be +/- a quarter of an inch and nobody would notice. Use common sense, and work in inches if you prefer.

MattiJ
01-23-2017, 11:16 AM
There are very good reasons for the actual sizes of piping being what they are. A little study of the history would reveal them to you.

But what the hell does it matter what the actual sizes are? They are not a mystery, there are tables of sizes all over the place. Just deal with it and stop whining about it.

Not everything has to fit into a metric sized box. You'll be wanting your bloody vegetables grown to standard metric weights and sizes next.

I'm well aware of the "very good" historical reasons.

Metric standard vegetables?
We already have them, 1kg bag of apples or potatoes. How else they would match the pre-bagged product weight if they don't have 5pcs 200 gram apples?
I'm guessing you still buy apples by barrel, just not sure which version of the dozen barrel versions.

cameron
01-23-2017, 12:08 PM
I'm well aware of the "very good" historical reasons.

Metric standard vegetables?
We already have them, 1kg bag of apples or potatoes. How else they would match the pre-bagged product weight if they don't have 5pcs 200 gram apples?
I'm guessing you still buy apples by barrel, just not sure which version of the dozen barrel versions.

No, I pick my apples off the tree, they're different sizes, different shades of red and some have worms in them and they taste a hell of a lot better than anything you can buy in a 1kg bag.

J Tiers
01-23-2017, 01:30 PM
I'm well aware of the "very good" historical reasons.

Metric standard vegetables?
We already have them, 1kg bag of apples or potatoes. How else they would match the pre-bagged product weight if they don't have 5pcs 200 gram apples?
...

Easy... the sorter has a bunch of weighing stations and a chute for each. The machine knows the next up weight in each, and opens the doors for the right weight within the spec. Seen it in a potato sorter, apples would be similar

loose nut
01-23-2017, 01:54 PM
It was reference to the funky nominal pipe sizing. If you buy 1" pipe from hardware store it has a 1.1" hole and 1.3" inch outer diameter.
And the same with goddammit pipe threads, 1/4" BSPT thread has diameter a bit over 1/2" :mad:

You cant avoid those even here in metric Europe, BSP pipe thread with 55-degree flanks is the official standard on lots of things. To add confusion some NPT/BSP or NPS/BSPP fitting are close enough to mate but not properly.

Maybe you should standardize on one system like we have, NPT.

Who cares what the actual dimensions are, it isn't necessary. 1" pipe fits 1" elbow or 1" tee etc. No muss no fuss, no BSPT, no 55 Deg threads and NO METRIC. Have a nice day.

BCRider
01-23-2017, 02:15 PM
Loose nut, WE have standards here in Canada? ! ? ! ? THAT'S FUNNY STUFF! This is the Land of Confusion. We are officially metric but tools are sold with imperial as well as metric and we can still even buy imperial only tape measures. Yet building plans typically come in really odd metric values and 2x4's are sold in the stores as 2x4's while sheet goods can only be found in metric any longer from near as I can find.

So I'm not sure I'd want to be the kettle calling out the pot on this issue of national standards. We simply ain't a good example of any such planning and forethought... :D

As for the Stirling plans? It seems to me to be a pretty easy conversion to pick out machine screw sizes to sub in for the metric screws. A few notes on hole sizes for drilling and threading and it's done. The adapting of things like 10mm vs 3/8" stock have a lot more ramifications. For that I'd say it's a "pay me now or pay me later" sort of deal. There's a lot to be said for JTiers' (I think it was) suggestion to start with thicker stock and mill to the metric thicknesses then cut out the parts. But if that is simply too wasteful for you to bear then there's no way around it. You would need to go through the plans and modify the measurements wherever the change in thickness alters matters.

In many cases only one side of a part needs to be accurately located. The holes for the screws may not be centered in the thickness but generally they would be close enough. The rare time that two parts rely on the accurate thickness of material then you'd likely want to mill that thickness down from something heavier. Otherwise you'd be chasing your tail a whole lot trying to be sure you catch all the changes needed to make up for even a small change in part thickness in the critical areas.

cameron
01-23-2017, 04:41 PM
Regarding the metric equivalent chart loose nut posted, the first reference in post#23, 10-32 is a much closer equivalent to M5X0.8 than 10-24.

32tpi is 0.79375mm pitch.

10-24 is a bit of an abomination, suitable only for what G.H. Thomas called "garden engineering".

cameron
01-23-2017, 05:09 PM
Loose nut, WE have standards here in Canada? ! ? ! ? THAT'S FUNNY STUFF! This is the Land of Confusion. We are officially metric but tools are sold with imperial as well as metric and we can still even buy imperial only tape measures......
.

Yes, harder to find and less selection than the inch/metric tapes, but much nicer to work with.

We can also buy metric only, even harder to find etc, but if you do any work at all in metric you should have one.

loose nut
01-23-2017, 07:07 PM
Loose nut, WE have standards here in Canada? ! ? ! ? THAT'S FUNNY STUFF! This is the Land of Confusion. We are officially metric but tools are sold with imperial as well as metric and we can still even buy imperial only tape measures. .

Yes we do. ASTM, ASME ETC. We have our own equivalent (almost identical) but most refer back to those standards.

I was only referring to pipe etc. (and giving a little dig) and your right about the rest, glad of it. I like to think that many of our people have given the government the finger when it comes to having the metric systems shoved down our throats. Not that it bothers me anymore, being retired I use what ever I want. The trades here still use Imperial measurement and very little Metric. Ask a carpenter to get a 50 by 100MM board and you will probably get a hammer thrown at you, a 16 oz. one at that.

FYI - metric and Imperial pipe and fittings (not the threads) are close enough in size to be interchangeable. Most are stamped with both specs. When I was still working for a living and not for fun we frequently mixed metric and Imperial pipe and fittings. What ever we received from the supplier.

malbenbut
01-25-2017, 04:53 AM
Just divide mm by 25.4. calculators are very cheap to buy.

MBB

3jaw
01-25-2017, 07:06 AM
Just divide mm by 25.4. calculators are very cheap to buy.

MBB

This ^^^

J Tiers
01-25-2017, 09:31 AM
Just divide mm by 25.4. calculators are very cheap to buy.

MBB

Is there an echo in here?

Most suggested this already. The question really seems to be whether to do a full conversion to US hardware, or keep the metric, and whether to try to adapt all the dimensions to US materials.

I still think the most sensible plan is to use the mm dimensions, converting just so the dials on the machines make sense, and then use metric hardware. If a couple sizes of metric tap are needed, so be it, buy them.

BCRider
01-25-2017, 01:17 PM
The problem with the metric taps is that they require metric fasteners. Now while automotive and industrial size metric screws are common in a variety of grades and styles these days the smaller size stuff isn't so common. The only really easily found smaller size metric hardware I've seen without searching for it is the cheap and cheezy computer related hardware.

It's not that big a deal to figure out a close match to some number size screws. And if Mr Fixit is anything like me he's already gathered and bought an assortment of number size hardware and would like to use that on shelf supply of Allen cap screws or Allen button head screws or Allen flat head screws in number based sizes.

reggie_obe
01-25-2017, 01:32 PM
The problem with the metric taps is that they require metric fasteners. Now while automotive and industrial size metric screws are common in a variety of grades and styles these days the smaller size stuff isn't so common. The only really easily found smaller size metric hardware I've seen without searching for it is the cheap and cheezy computer related hardware.


Not to worry.....
The Portland, Or. Hom Dee has 3 and 4mm socket cap, hex flat head and hex button head cap screws in stock.

MattiJ
01-25-2017, 01:54 PM
Not to worry.....
The Portland, Or. Hom Dee has 3 and 4mm socket cap, hex flat head and hex button head cap screws in stock.

Or order online the small sizes. You get billion of small nuts and screws before its too heavy, M3 nuts are something like 2usd per 1000pcs. Probably enough for your grandkids..
Anything smaller than M3 or M4 or any other head than slot/phillips is also difficult to find here, easiest to order online.

lakeside53
01-25-2017, 02:06 PM
If it just about a small piece of material like the pipe.. make THAT part to metric sizes and stay with the plans. Working in metric is no issue...

BCRider
01-25-2017, 03:03 PM
Not to worry.....
The Portland, Or. Hom Dee has 3 and 4mm socket cap, hex flat head and hex button head cap screws in stock.

I'm impressed! Seriously! The HD up here in our so called metric standard land does not carry that sort of product.

Online ordering is certainly possible. In fact with the constant closure of small hobby related shops it is becoming the best way to order many small items. It also seems like some of the more industrial based suppliers are not interested in any street traffic either. For years now the local Acklands-Grainger outlets have only sold to me if I fake a company name. And only a few years ago when I went into the local Fastenal to buy about $50 worth of boxes of screws to expand my stock I was told that they no longer did non commercial sales.

But some of us have already invested in a stock of number screw sizes. And rather than buy MORE sizes in metric just to hand down to someone's grand kids I know I'd rather just adapt the drawing to let me use what I have on hand already. So for me switching the drawing dimensions and choices to use the stock and tools already on hand would be a very easy choice. And for anyone with a similar habit of buying a box of screws when they only need a few I'd figure that it would be similarly attractive to do a little home work to avoid buying a range of metric fasteners to go with the number and fractional sizes.

It isn't like model size projects of this sort put a serious load on the fasteners either. So selecting the next size number or fractional screw up or down is likely going to be determined more by the room for the screw head so the heads do not protrude past an edge or foul some other part. An hour or so going over the drawing, measuring on-hand hardware and making some notations and it would be ready to go.

reggie_obe
01-25-2017, 03:19 PM
I'm impressed! Seriously! The HD up here in our so called metric standard land does not carry that sort of product.

Even if it isn't a stocked item, it can be ordered and shipped to the store in a couple of days at no extra cost. That's S.O.P. in every Home Dee in the continental US, probably true even in Canukistan.

BCRider
01-25-2017, 03:23 PM
Even if it isn't a stocked item, it can be ordered and shipped to the store in a couple of days at no extra cost. That's S.O.P. in every Home Dee in the continental US, probably true even in Canukistan.

Can't say as I've ever tried that other than to get some item in a color or size not currently in stock. I'll keep it in mind as an option to online ordering. Thanks!

JohnAlex141r
01-25-2017, 03:32 PM
I'm impressed! Seriously! The HD up here in our so called metric standard land does not carry that sort of product.

I dunno - I do everything in metric (*) (as does the company my partner works for - a construction company) and the last time I wanted some heavy duty electrical cable, I measured it metres, converted that to feet or inches or whatever, went to Home Depot up here in Canada, and was told "hold on a minute - I have to convert that to metres for our measuring machine".

A young welder I know, who did work for a small "job shop", when asked if plans were metric or inch, he said that it was about 50/50. He could work to inches. Not to feet or yards (had no clue what a foot was), but knew what an inch was.

So, despite what some fellow Canadians say, there's lots of metric work going on here.

note - was machining some scrap brass that was 12.7mm thick - half an inch for those who must measure that way. ;-)

loose nut
01-25-2017, 04:58 PM
I'm impressed! Seriously! The HD up here in our so called metric standard land does not carry that sort of product.

.

When the country first "went" metric all the hardware's, HD etc. stocked metric nuts and bolts. Over time they quit, nobody was using them. If you want metric fasteners, in many areas, you have to go to an industrial supplier or go online. Both places require minimum orders when you need one or two. A hardware will sell you just a few imperial fasteners.


I dunno - I do everything in metric (*) (as does the company my partner works for - a construction company) and the last time I wanted some heavy duty electrical cable, I measured it metres, converted that to feet or inches or whatever, went to Home Depot up here in Canada, and was told "hold on a minute - I have to convert that to metres for our measuring machine".

A young welder I know, who did work for a small "job shop", when asked if plans were metric or inch, he said that it was about 50/50. He could work to inches. Not to feet or yards (had no clue what a foot was), but knew what an inch was.

So, despite what some fellow Canadians say, there's lots of metric work going on here.

note - was machining some scrap brass that was 12.7mm thick - half an inch for those who must measure that way. ;-)

Students get taught in metric and then go to work in the trades and get a rude awakening, most but not all trades or companies still use Imperial (different places different ways). Yes some places use metric but most still work the old way. Parts and materials come out of the US so it is easier to work in Imperial. This may change in the future, or not? Doesn't really matter, use what you want nobody cares.

MattiJ
01-25-2017, 05:13 PM
I dunno - I do everything in metric (*) (as does the company my partner works for - a construction company) and the last time I wanted some heavy duty electrical cable, I measured it metres, converted that to feet or inches or whatever, went to Home Depot up here in Canada, and was told "hold on a minute - I have to convert that to metres for our measuring machine".



Lots of construction related is informally referred in inches even in here, like "six inch nails" or 2"x4". But nobody would ask for 2" wood screws or a half inch plywood. Or god forbid mystery gauge sheetmetal.

We have switched to metric system in 1886 so you canucks can expect to use inches at least another 75 years :D

mklotz
01-25-2017, 05:14 PM
Trying to use two measurement systems simultaneously will ultimately get you in trouble. Remember the Gimli glider?

MattiJ
01-25-2017, 05:23 PM
Trying to use two measurement systems simultaneously will ultimately get you in trouble. Remember the Gimli glider?

Or NASA's mars orbiter.

J Tiers
01-25-2017, 05:23 PM
The US accepted metric in 1878 or so, but we still use imperial mostly.

But everything is available from places like McMaster-Carr in metric as well as Imperial, so hardware like nuts and bolts, screws, etc should be absolutely no issue. Same with taps, and to some extent materials as well.

The biggest issue is the dials on the machines. To change that would require new feedscrews and feed nuts, as well as dials. And then there would be a problem with Imperial, which there is a gigaton of still installed everywhere.

MattiJ
01-25-2017, 05:30 PM
The US accepted metric in 1878 or so, but we still use imperial mostly.

The biggest issue is the dials on the machines. To change that would require new feedscrews and feed nuts, as well as dials. And then there would be a problem with Imperial, which there is a gigaton of still installed everywhere.

8 TPI leadscrew on my lathe, 2mm on the crossfeed and 1/10" on the topslide. Converted crossfeed is kind of stupid because its now with 0,04mm graduation and markers every 0,4mm but getting used to it was suprisingly fast. Luckily you hardly need any other than the crossfeed scale on the lathe.

JohnAlex141r
01-25-2017, 06:06 PM
Whatever works - things change. I learnt in "thous" and lots of BA fasteners were used, but I went through metric here in Canada in school (as did anyone who still of working age, or are lucky to be already retired at a fairly young age)

It did take me a bit to adjust to making models in metric, when I went that way about 25 years ago.

Not sure what my larger (inch, BSW fasteners) lathe has - except that it has metric transposing gears so the QC gearbox plate's metric side is what I use. It has metric dial indicators on two axes for those.

My inch-based olde english miller was purchased from a fellow who installed a DRO on it - have *absolutely* no idea what the feed screws are.

My CNC mills? they don't care, but I expect they are all metric (all fasteners are, anyway, and the config files assume metric ball screws)

My 3D US made printer? Metric. As is all the sw. and PLA extrusion material for it.

Most of the plans I use from the UK and USA (read the books on the supporter of this site!) are metric, although a Christmas present Southworth Pump "casting kit" from the UK has plans in inches with BA fasteners. It comes with O rings, so I'll use inch SS rod in it, rather than replace the rings.

I think most people don't care; just build it. Lots of really nice things are built to metric dimensions and fasteners, as are inch-based stuff.

It's up to the builder to make the model work, isn't it??

Juergenwt
01-25-2017, 06:16 PM
Let us all thank our former Pres. Reagan. The great communicator. Thanks to him the US and Canada will for generations to come continue to struggle with both systems.
Maybe our new Pres. will shift it all back to imperial - which would damage our export even more - or maybe he will finally force our remaining imperial industry to convert to metric and our schools to teach metric only. Remember you can still ask for a pint of beer, even if getting a 0.5 L (1/2L) glass or you can still ask for a pound of sausage, even if getting a 0.5kg (1/2kg). As for the thousands of old imperial machines in all the medium-small-and garage type shops......forget it. Your children are not interested in manufacturing and for building hobby projects they will do just fine. Most are old clunkers now and will be ancient when you die.
The building and construction industry will not change until the Chinese start providing the first prefab units . It will happen and they won't know what hit them. Just like the Auto industry.
This is the company with the most complete offering on anything metric: http://mdmetric.com
Lots of technical info.

BCRider
01-25-2017, 07:52 PM
It's the mixture that I find annoying to work with. I'm of the age where I learned metric in school due to the science classes but used imperial for my hobby and when working with my father. So to some extent I'm "bimeasuremental".

Years ago when my model airplane hobby was my main interest I thought about going metric for my own home shop. But the balsa wood then and now is all sized in fractional inch thicknesses here in North America. So it simply wasn't worth fighting the head wind.

But my bicycles and motorcycles are all metric. So I get lots of practice working with both.

If I were in MrFixit's position of building a plan all in metric I'd be fine with working with metric. Might be fun to actually use my metric dial calipers and metric micrometers a little more often. But the problem would be if the plan calls for 10mm thick plate stock to make some parts from. That's .394". So do I/we try to make do with .375"? Or do we try to find some 7/16" which would be just over 11mm? Or do we start with some 1/2" and mill it down to 10mm and work with that? There's actually not all that much work to milling it down so I might well do something like that.

But I would take the time to convert over to number size machine screws since I've got a pretty good assortment and only so many years left to use them all.

wombat2go
01-25-2017, 08:04 PM
I am metric, being Australian, migrated to Michigan.
In the hobby shop, I am finding some convenience working in metric.
For example 25.4 mm dia hr 4130 is useful at 25.0 , same with 15.87, 12.7 and 6.3 etc.
So I now buy oilite and ball bearings in metric sizes.

Over past 20 years in USA, I have noticed increasing acceptance of metric.
I had one client doing some export, that elected to do all eng drawings in metric where possible.
Last week I looked up on internet search the Youngś and Shear for 6061,
expecting to have to convert. But most hits had the values in GPa.
Design by computational modelling is all mks and will surely kill off the old British units.

My son year 6, is bringing homework in metric units as well as the obsolete units.

The biggest unit problem in my day job ( metal heating) is the Fahrenheit.
I can say it has caused a lot of problems over the years, engineering errors etc.
Especially under 700, nobody can be sure whether Fahrenheit or Celcius is the unit referred to.
Also it is not a multiple like most conversions, having the 32 offset, , so we can't convert mentally.
Another problem commonly occuring with Fahrenheit, is when we need absolute temperature differences.
So I think Fahrenheit is becoming obsolete too, - helped by instrumentation with a button to convert!

Dan_the_Chemist
01-25-2017, 08:24 PM
Probably not important for a coffee cup sized Sterling engine, but when converting metric to imperial you need to avoid cumulative error.

10 mm = 0.393701 " It's the stuff to the right of the second three (.000701) that can cause problems. For example, lets say you had a gizmo with holes every 10 mm for a distance of 1 meter.... If you calculated the distance between the holes to be 0.394" and drilled the holes by shifting your table 0.394" from the last hole to the next hole, then by the end of the run you would have a total center to center distance of 39.400" However, the correct answer is 39.3701"... almost 30 thousandths off.

The better way to do it is reference everything to an X,Y,Z = 0,0,0 Add up the plan dimensions in metric first to get the coordinates of any point, line, etc, and then convert the sum to imperial. So the first hole would be at X=0 mm, the second at X=10 mm, the third at X=20 mm, the fourth at X=30 mm. That way when you convert to X=0.000", X=0.394", X=0.787", X=0.118" you will never be more than +/-0.0005" off (on your calculation and rounding).

Not so important for a coffee cup engine. More important for big things that need to be very precise.

J Tiers
01-25-2017, 08:52 PM
But 25.4 is exact.

Mr Fixit
01-25-2017, 09:19 PM
We'll Group,

My friend and I have decided to use the 25.4 and double check the quick formula on Google that I originally used and to do a complete inch conversion. We will find or maybe even make everything from stock material to the new inch design.
We will keep you posted as we progress. Materials and plans this month, machining February 1st..


TX
Mr fixit for the family
Chris. :)

old mart
01-27-2017, 04:26 PM
At the museum, the lathe is imperial and the mill is metric, we just get on with it and amend drawings to suit. One of our older volunteers always gives us drawings in fractions of an Inch, we have a good laugh about that.

Alistair Hosie
01-27-2017, 05:06 PM
I doubt if you could truly get an absolutely perfect conversion unless maybe you used c n c or even then maybe not. The current thought of 25.4 mm per inch or 12.7 per half inch then approx. six mm for a quarter of an inch and three mm for an eight should be enough to teach most of us that these conversions are what are termed mathematically as nominal ( named conversions) and are as such not to be regarded as perfect.

It is crudely a bit like when I first started to cut say 6 pieces of wood all the same size on the table saw. Five were indeed perfect the sixth was a total disaster as I forgot to remove Approx. 3mm in each cut for the width of the saw teeth. LOL I never forgot that or did it twice.

J Tiers
01-27-2017, 07:00 PM
I doubt if you could truly get an absolutely perfect conversion unless maybe you used c n c or even then maybe not. The current thought of 25.4 mm per inch or 12.7 per half inch then approx. six mm for a quarter of an inch and three mm for an eight should be enough to teach most of us that these conversions are what are termed mathematically as nominal ( named conversions) and are as such not to be regarded as perfect.


Actually, 25.4 IS perfect. The inch is actually defined as such. Now, what you can dial in on a lathe or mill may never be perfect, unless by accident. And, if you DID hit that perfect number by a happy accident, probably most measuring instruments would tell you that it is not correct. Nothing is perfect except mathematics, and there is even some doubt there.

waumbek
01-27-2017, 08:48 PM
I just finished the Acute tool sharpening from Eccentric Engineering in metric and had a fun time with it. First time I'd worked in metric. Here's something that helped: my iPhone. I bought a wall mount for it and placed it right next to the lathe so I can say, "Hey Siri, what's half of .19 millimeters in decimal inches?"
Siri will convert back and forth from metric to imperial very quickly, and as you can see from my above example, will even divide the answer in half for lathe work. Granted, not everyone has an iPhone, but there are other voice activated systems and aps that can be surprisingly helpful. Someday I'll buy a DRO, but it's not nearly as essential as you might think and I suspect that those of us who own smartphones already have a solution.
Similarly, if you want to convert a set of plans, just put the phone on your drafting table and ask it!

regards, Charles Morrill

elf
01-29-2017, 05:08 PM
I was curious to see how hard it would be to convert a drawing from metric to imperial in Fusion 360. I chose the Coffee Cup Stirling Engine by Jan Ridders: http://www.projectsinmetal.com/free-metalworking-project-plans-the-coffee-cup-stirling-engine-by-jan-ridders/

Here's the model in Fusion 360:
http://img.photobucket.com/albums/v649/etfrench/Misc/Stirling.jpg

The link to the metric version in Fusion 360: http://a360.co/2jsUTGk
The link to the imperial version: http://a360.co/2kILETj

Fusion 360 makes it fairly easy to change the dimensions, but it was tedious to do them all. Quite a few of the dimensions could be changed directly and have the model update. Others had to be calculated and use Press/Pull commands to change the parts. The hard part was choosing whether to make a part larger or smaller and ensuring the mating part was changed as well.

dalee100
01-30-2017, 09:24 AM
Hi,

One of the handy features of OnShape is being able to draw in either metric or imperial. And then when generating the shop prints, it can auto-magically convert all dimensions for you.

So I draw many of my models in metric for study and then simply print them in imperial.

Dalee

elf
01-30-2017, 01:37 PM
All CAD programs can seamlessly convert between metric and imperial. What they can't do is convert the models to use standard sizes in either system.