Author Topic: Project Plans utilizing ?/32 of an Inch  (Read 1734 times)

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Offline Steven Owen

  • Posts: 409
Project Plans utilizing ?/32 of an Inch
« on: August 14, 2018, 04:02 PM »
Maybe it's just me, I don't understand why some wood workers insist on making project plans with cuts like 13 7/32 inches.  It's hard to get a Table Saw or track saw (for that matter) to cut a perfect line beyond 1/16 of an inch.  I found a plan for a cool coffee table.  I'm rounding all the measurements up to 16th's make the design more manageable.

It was a bit laughable to see coffee table plans utilizing a 1/32 scale for cuts given there's no space constraints that would require working in thousandths of inches. 

Even with the most high end blades, there's still a slight bit of blade wobble which make it very hard to hit 1/32 or a thousandth of inch. 

1/32 is the thickness of a slice of paper. I can't see that making much of a difference in a drawer cut.   It seems like the project could have been easily modified to be in 16th with zero impact on the cabinet.

Do you find theirs any projects where it makes sense to work 1/32 scale?
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Offline vkumar

  • Posts: 359
Re: Project Plans utilizing ?/32 of an Inch
« Reply #1 on: August 14, 2018, 04:06 PM »
I see your point.  1/32 " is too fine.

But to set the record straight. A sheet of paper is 0.004" thick. Thus 1/32" would be about 8 sheets of paper.
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Offline Ster1154

  • Posts: 62
    • WoodEyes Woodworks
Re: Project Plans utilizing ?/32 of an Inch
« Reply #2 on: August 14, 2018, 04:06 PM »
I personally don't understand it either.  I'd rather the plans convert to metric and use millimeters if they're going to be that precise (and they may have been converted from metric to Imperial for that matter) since it'll be MUCH easier to do the math w/ millimeters than 32nds of an inch.

I was asked to build some cabinets that called for 1/32" tolerances and had to politely explain that that's going to be quite the challenge when working with variable materials such as wood.  With steel it's much easier but with anything organic it's going to be darn near impossible. 

Offline RKA

  • Posts: 1256
Re: Project Plans utilizing ?/32 of an Inch
« Reply #3 on: August 14, 2018, 04:38 PM »
Are you sure those project plans weren't natively in metric and then converted to imperial for those people whose tools are strictly imperial?  Then it would make sense that they provide the dimensions in 1/32's.  Have you asked for the project plans in metric?
-Raj

Offline Dick Mahany

  • Posts: 384
Re: Project Plans utilizing ?/32 of an Inch
« Reply #4 on: August 14, 2018, 04:45 PM »
I do Nanometers, Microns, Millimeters and Decimal Inches.  Can't stand fractions.  However, when one considers that 1/32" is just under a millimeter by 25%, then those dimensions can matter when it comes to joinery or squareness depending on the application.  Also, with many designs being produced with programs such as Fusion 360 and Sketchup, then many plans can be dimensioned with 1/32" callouts depending on the precision settings made during the design.
« Last Edit: August 14, 2018, 04:49 PM by Dick Mahany »

Offline Steven Owen

  • Posts: 409
Re: Project Plans utilizing ?/32 of an Inch
« Reply #5 on: August 14, 2018, 04:56 PM »
Are you sure those project plans weren't natively in metric and then converted to imperial for those people whose tools are strictly imperial?  Then it would make sense that they provide the dimensions in 1/32's.  Have you asked for the project plans in metric?

Several of the plans are from US sites.  Who knows, they may have originated from Europe.  I would assume many of the US and Canadian wood working magazine are sometimes receiving and modify plans from people in Europe.

I would assume as long as you round corresponding cuts to the nearest 16th of an inch your project should remain square.

The only time I've seen 1/32 of an inch throw off joints is with mitre joints, box joint and dovetails. 
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Offline koenbro

  • Posts: 58
Project Plans utilizing ?/32 of an Inch
« Reply #6 on: August 14, 2018, 07:48 PM »
I, rather crudely, convert 1/32” as 1mm and 1/16” as 2mm. That said, I design in metric using Fusion360. In my own joinery (small Domino) I generally get about a 2mm precision. Anything worse is noticeable.


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Offline Steven Owen

  • Posts: 409
Re: Project Plans utilizing ?/32 of an Inch
« Reply #7 on: August 14, 2018, 11:15 PM »
I, rather crudely, convert 1/32” as 1mm and 1/16” as 2mm. That said, I design in metric using Fusion360. In my own joinery (small Domino) I generally get about a 2mm precision. Anything worse is noticeable.


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Woodpeckers and Incra changed things with their newer T-squares and rulers.  Before Woodpeckers and Incra, you never would see projects with 14 7/32 inches. 

I think some people are repurposing plans from Europe too.   
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Offline kevinculle

  • Posts: 231
Re: Project Plans utilizing ?/32 of an Inch
« Reply #8 on: August 15, 2018, 08:18 AM »
I find 1/32" (or 1mm) to be the level of precision needed in quality woodworking, whether the piece is dimensioned to even numbers or not is irrelevant but holding that tolerance on reveals and fits of mating pieces is straightforward.  My Incra TSIII tablesaw/router table fence system locks to 1/32" increments with dead nuts repeatability and can be dialed in between those fixed pooints when needed.

Offline Steven Owen

  • Posts: 409
Re: Project Plans utilizing ?/32 of an Inch
« Reply #9 on: August 15, 2018, 10:19 AM »
I find 1/32" (or 1mm) to be the level of precision needed in quality woodworking, whether the piece is dimensioned to even numbers or not is irrelevant but holding that tolerance on reveals and fits of mating pieces is straightforward.  My Incra TSIII tablesaw/router table fence system locks to 1/32" increments with dead nuts repeatability and can be dialed in between those fixed pooints when needed.

With a large shop and a full sized saw table, that shouldn't be an issue.  Most of home shop users don't have room for that kind of equipment.

The Parallel guides don't measure in units lower than 16th's.  Without a track saw, the Woodpeckers T-Square becomes the only viable option to cut a measurement like 17 9/32 inches. 

I'd rather work in MM than inches.  Most of these ?/32 measurements are the result of converting 32 MM standard project plans into inches.   
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Offline Sparktrician

  • Posts: 3661
Re: Project Plans utilizing ?/32 of an Inch
« Reply #10 on: August 15, 2018, 11:33 AM »
I'd rather work in MM than inches.  Most of these ?/32 measurements are the result of converting 32 MM standard project plans into inches.


Same here.  Metric is so much easier. 
- Willy -

 "Remember, a chip on the shoulder is a sure sign of wood higher up." - Brigham Young

Offline Michael Kellough

  • Posts: 3563
Re: Project Plans utilizing ?/32 of an Inch
« Reply #11 on: August 15, 2018, 12:54 PM »
Maybe it's just me, I don't understand why some wood workers insist on making project plans with cuts like 13 7/32 inches.  It's hard to get a Table Saw or track saw (for that matter) to cut a perfect line beyond 1/16 of an inch.  I found a plan for a cool coffee table.  I'm rounding all the measurements up to 16th's make the design more manageable.

It was a bit laughable to see coffee table plans utilizing a 1/32 scale for cuts given there's no space constraints that would require working in thousandths of inches. 

Even with the most high end blades, there's still a slight bit of blade wobble which make it very hard to hit 1/32 or a thousandth of inch. 

1/32 is the thickness of a slice of paper. I can't see that making much of a difference in a drawer cut.   It seems like the project could have been easily modified to be in 16th with zero impact on the cabinet.

Do you find theirs any projects where it makes sense to work 1/32 scale?

I agree that it’s easier to work in metric but your premise (highlighted in bold above) is wrong. When the splinter guard is in good condition it’s not very difficult to make a cut within 1/100th of an inch of the mark, assuming you have the ability to make that fine a mark. It is somewhat more difficult with most tablesaws due to the rather crude fences but not with my first edition Paralok fence. The feature that attracted me to the Festool track saw was the ability to get the same precision in the field at angles other than parallel to the edge of the work.

I’d work in 1/100” increments all the time if it wasn’t so hard to see them. In fine work it does make a visible difference. If tape measures maintained 1/32” increments for the full length I’d still work in Imperial and split the 32nds in halves or thirds to get closer but such tape measures are hard to find and or the tongues are unreliable. Using metric measures splitting millimeters yields about 1/50th inch accuracy which is usually close enough. I generally only go finer when working metal.

If you’re being paid to build things designed by other people you better learn how to do that accurately. If you just copying other people’s designs for your own use feel free to changes the system of measurement to suit yourself. You ought to test all the measurements anyway. I wouldn’t trust that there isn’t a typo or other mistake. Better yet build the thing in CAD.

Offline Dick Mahany

  • Posts: 384
Re: Project Plans utilizing ?/32 of an Inch
« Reply #12 on: August 15, 2018, 01:14 PM »

I’d work in 1/100” increments all the time if it wasn’t so hard to see them. In fine work it does make a visible difference. If tape measures maintained 1/32” increments for the full length I’d still work in Imperial and split the 32nds in halves or thirds to get closer but such tape measures are hard to find and or the tongues are unreliable. Using metric measures splitting millimeters yields about 1/50th inch accuracy which is usually close enough. I generally only go finer when working metal.

If you’re being paid to build things designed by other people you better learn how to do that accurately. If you just copying other people’s designs for your own use feel free to changes the system of measurement to suit yourself. You ought to test all the measurements anyway. I wouldn’t trust that there isn’t a typo or other mistake. Better yet build the thing in CAD.

I have found that using metric tape measures has greatly improved my fitting (over imperial tapes) and it seems quite easy to split millimeters at least in half to yield as you have said ~1/50".  I typically like to use either the Flat Back metric tape or the true 32 tapes from FastCap.  I can't vouch for the accuracy of either tape, however the precision with them is excellent because I only use a single tape on a given project where possible.
« Last Edit: August 15, 2018, 01:25 PM by Dick Mahany »

Offline Sparktrician

  • Posts: 3661
Re: Project Plans utilizing ?/32 of an Inch
« Reply #13 on: August 15, 2018, 02:13 PM »
I prefer using my Hultafors Talmeter tapes for accuracy.  Amazon has them, but watch out for the utterly ridiculous shipping fees. 
- Willy -

 "Remember, a chip on the shoulder is a sure sign of wood higher up." - Brigham Young

Offline HarveyWildes

  • Posts: 792
Re: Project Plans utilizing ?/32 of an Inch
« Reply #14 on: August 15, 2018, 02:50 PM »
For woodworking, measurement accuracy depends on what I'm doing.  But for any given activity, measurement only gets you so far, and if I need better accuracy than that, then I use other techniques to get it - fences, stops, jigs, design that allows for sloppy measuring and still looks good, etc.  Generally, I try to work so that measuring is the last resort, but sometimes you just have to do it.

Offline Steven Owen

  • Posts: 409
Re: Project Plans utilizing ?/32 of an Inch
« Reply #15 on: August 15, 2018, 04:47 PM »
I prefer using my Hultafors Talmeter tapes for accuracy.  Amazon has them, but watch out for the utterly ridiculous shipping fees.

I’d rather stick with the Woodpeckers T-Sqaure to avoid parralex vision error that can happen when using measuring tapes.  Most of the time when you run into ?/32 measuresements, it’s on doors, drawers, trim, and interior cabinet pieces.
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Offline DeformedTree

  • Posts: 187
Re: Project Plans utilizing ?/32 of an Inch
« Reply #16 on: August 16, 2018, 12:12 AM »
This is one of my biggest beefs with imperial still being around.  People think they can convert or worse due soft conversion/dual dimensioning.   In the end, something is either inch or metric, not both.  Problem is you simply don't know what they started with. It's part of my issue with Festool is their information on the website/etc in the US now is in converted numbers which have rounding and such involved to get them to dumb fractions.  You have to go to other region sites to actually figure out what the dimensions of things are.   

This is why in engineering when in imperial we do it in decimal inches.  Fractions were banned by companies and standards organizations in the 50s. Also they don't really work with computers.  If something is in inch you can work with it, but it has to be in decimal.   Otherwise you end up with terrible tolerance stack error from things being.  3/8,  so that's .375, which then someone made .38 because they used sheet tolerance, and then someone else makes it .4 for a looser tolerance, and now that fractional value of .375 is lost.  Someone stacks up 3 things .375 thick and thinks it is now 1.2 thick, when it's 1.25.  But when you start getting things like 3/4" (20mm) then you are truly doomed.  Which is it, these are not the same, and without knowing which is the native value it's all over.

As was covered above, mm work great for general stuff since 1mm is a very good base tolerance value. Lots of legacy things were draft up calling out tolerances of plus/minus .030",  So 1mm is even a bit looser, but makes all the math so darn easy.  If your under 1mm, your using a machining center of some form, and now can progress down to 0.1mm before you have to regroup/think things again.

While I have massive problems with Festool forcing imperial on North America and they really messed up by using fractions, the one thing they did get right was not putting dual scales on the tools, that would have been a sin far greater than going imperial.  To many folks see it as a solution, when it's really so much worse.

Sparktrician. thanks for the link on a purely metric tape in the US, those are something that's darn near impossible to find, yet highly wanted.  Makes for some nice gifts for work.

Offline Michael Kellough

  • Posts: 3563
Re: Project Plans utilizing ?/32 of an Inch
« Reply #17 on: August 16, 2018, 12:13 AM »
I prefer using my Hultafors Talmeter tapes for accuracy.  Amazon has them, but watch out for the utterly ridiculous shipping fees.

I’d rather stick with the Woodpeckers T-Sqaure to avoid parralex vision error that can happen when using measuring tapes.  Most of the time when you run into ?/32 measuresements, it’s on doors, drawers, trim, and interior cabinet pieces.

Parallax error? I guarantee the thickness of the beveled edge of that T-square is at least 5 times the thickness of the Hultafor tape. Measuring with that red stick is where you’ll get parallax error.

Plus, it’s only 2 feet long.

Oh, I get it now, you don’t want to measure, just stick a pencil in a hole and the Woodpecker T-square only provides holes every 1/16”. Hence the annoyance with a plan that specifies a point in-between two holes. That’s a problem...

So you adjust the plans to sixteenth’s, stick a pencil in a hole and drag out a line. Now you’ve got a mark that is nearly a full millimeter wide. Which part of that fat line will you cut? Left, right, or middle?

If you want to drag lines with precision try the Incra rules. They’re available with holes up to 1/64”. Plus you use a pencil half as fat as the WP tool requires. And if you want to actually use the edge of the tool to measure and mark, the thin stainless steel edge is way less likely to induce parallax error.

Incra rules are also available in tenths and fiftieths if you want to go decimal inches.
« Last Edit: August 16, 2018, 09:15 AM by Michael Kellough »

Offline jimbo51

  • Posts: 436
Re: Project Plans utilizing ?/32 of an Inch
« Reply #18 on: August 16, 2018, 09:54 AM »
If you want to discuss complex measurements, consider this information from Lee Valley.

"the chrome-tanned leather is slightly more than 1/16" (about 4 oz) thick"

Offline Steven Owen

  • Posts: 409
Re: Project Plans utilizing ?/32 of an Inch
« Reply #19 on: August 16, 2018, 10:54 AM »
I prefer using my Hultafors Talmeter tapes for accuracy.  Amazon has them, but watch out for the utterly ridiculous shipping fees.

I’d rather stick with the Woodpeckers T-Sqaure to avoid parralex vision error that can happen when using measuring tapes.  Most of the time when you run into ?/32 measuresements, it’s on doors, drawers, trim, and interior cabinet pieces.

Parallax error? I guarantee the thickness of the beveled edge of that T-square is at least 5 times the thickness of the Hultafor tape. Measuring with that red stick is where you’ll get parallax error.

Plus, it’s only 2 feet long.

Oh, I get it now, you don’t want to measure, just stick a pencil in a hole and the Woodpecker T-square only provides holes every 1/16”. Hence the annoyance with a plan that specifies a point in-between two holes. That’s a problem...

So you adjust the plans to sixteenth’s, stick a pencil in a hole and drag out a line. Now you’ve got a mark that is nearly a full millimeter wide. Which part of that fat line will you cut? Left, right, or middle?

If you want to drag lines with precision try the Incra rules. They’re available with holes up to 1/64”. Plus you use a pencil half as fat as the WP tool requires. And if you want to actually use the edge of the tool to measure and mark, the thin stainless steel edge is way less likely to induce parallax error.

Incra rules are also available in tenths and fiftieths if you want to go decimal inches.

I have the Incra T-Sqaures up to 18 inches.  The Woodpeckers T-squares are more use for larger cabinet cuts that should never require ?/32 of an inch cuts.  That’s just bad planing or a 32 mm project that should have been done in metric instead.
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