Cosman "piston fit drawer", a good idea?

Re: Cosman "piston fit drawer", a good idea?

Luke Herzberg

>There was a good article on humidity and movement in the last FW (or PW??) and drawer clearances were discussed as well.

- Luke

Re: Cosman "piston fit drawer", a good idea?

Felix B.

>I agree - 0.002" clearance is more overkill then a mark of craftsmanship. Does it take skills to fit drawer with 0.002"? Yes, but is it practical? No. But this is the whole separate topic that occasionally pops up here.

The way I see it - that is, if anyone cares at all - craftsmanship is not necessarily defined by super-tight tolerances, absolutely flat surfaces, perfectly spaced dovetails, etc. Why? Well, because these results are easily achieved using machines these days. On the other hand, as I mentioned earlier, if this perfection is achieved by hand tools, then there is a question: is it really necessary to perfect it so much?

Personally, there is nothing wrong with 1/16" clearance of a 36"-wide drawer...

Or may be I am just babbling at the end of the work day :)

F.

Re: Cosman "piston fit drawer", a good idea?

Clay C in Miami

>I haven't seen the DVD, but in looking at a lot of pieces, I don't remember seeing piston-fit drawers that were more than about 18" wide or 5" tall, and most are smaller. It seems that drawer height might be a more worrisome limit than width.

Clay

Re: Cosman "piston fit drawer", a good idea?

Jim Shaver - Oakville, Ontario

>Hi Clay,

That is what I was thinking myself. If the drawer face is indeed inset then it stands to reason that a solid drawer face over 4 ot 5 inches with seasonal movement might be a concern. I am sure that there are work arounds, like veneering the drawer face to a solid ply or core material and so on...but I think seasonal movement could be an issue.

take care,

Jim

By the way I have this dvd and I think it may well be Rob's finest.

Re: Cosman "piston fit drawer", a good idea?

Dan Clermont in Burnaby

>Hi Bill,

That is a wide drawer. I think if you were using quartersawn material most of the movement would be vertically.

2 thou is tight and if made during your humid season probably a good fit. If it starts to stick remove more material.

Rob had his piston fit drawers on display at our woodshow in the Vancouver area last fall during out rainy season. It was starting to stick so he took a couple of shavings off each side so it would move freely keeping in mind that in a couple of weeks it would be back n the cold, drier climate of eastern Canada and taking too much off might make it rack.

I do agree with Jim that the Draw making DVD is the best of Rob's DVD's to date although I haven't seen his M & T

Dan CLermont

Re: Cosman "piston fit drawer", a good idea?

Ed Mulligan, Cape Cod

>Bill -

I haven�t seen the video but I presume Rob advocates a .002� clearance at maximum moisture content. Obviously if you aim for .002� clearance now in the dry winter season the drawer will expand and get stuck in the opening as more humid conditions develop during the summer.

For smooth drawer operation the side-to side-clearance should be as tight as possible without rubbing. 1/32� of slop is way to loose. If the fit is loose the drawer might skew in the opening and jam or be difficult to operate. If well-fitted you should be able to shut an open drawer by pressing lightly with one finger on the extreme left or right of the drawer front.

I don�t know anyone who uses feeler gauges to determine clearance. For winter conditions start with the drawer a shaving or two larger than the opening and carefully plane one shaving at a time until the drawer operates smoothly. Then take off a couple more shavings on each side to allow for expansion to summer dimensions. You�ll still have that piston fit.

Vertical clearance doesn�t have much to do with smooth operation, so long as it is within reason. For a 9� high drawer I would allow at least 1/16� of vertical clearance in dry conditions, maybe more depending on species.

Ed

each piece shipped with a well tuned plane

bill tindall

>It is sounding to me like each piece of case goods shipped with its piston fit drawer needs to include a plane so the owner can continue to adjust as necessary, not only as a result of one season's change, but also in response to the aging of the case over the next 200 years. It seems to me doubtful that a large case will maintain such drawer opening tolerances over time.

But, I can be conviced by data. Does anyone have a case with large piston fit drawers that has not required adjustment in the last 10 years? Or alternatively, for those with access to quality antiques (not the case here on the frontier), do they come with piston fit drawers? I never get to explore quality old furniture so I don't know what was done by the old masters who made stuff that survived the rigors of use.

More and more I am becoming influenced by what the "ancients" did that has survived for 200+ years. King Tut's stuff has survived for nearly 3000 years(see earlier report). Now that is construction technique to be emulated unless one is building disposable furniture. I am becoming skeptical of joinery and finishes that have not been time tested. Piston fit struck me as a recent fad, but I could be convinced that is not the case if it shows up in stuff built in 1750.

Re: Cosman "piston fit drawer", a good idea?

ThomD

>Getting tight clearances doesn't even require much in the way of skill. I haven't seen this particular video, but the method of fitting tightly is fairly simple. You just measure your stock from the opening, and then scribe stock thickness from the OAL, you will get tight fits that open up when you plane back.

Where the skill is required is in making the carcase to those dimensions.

For me I would only attempt tight drawersif I was absolutely sure it was the seasonal high for humidity. Which is the same as saying it won't be .002" for long.

Re: each piece shipped with a well tuned plane

Ed Mulligan, Cape Cod

>Bill -

I don't have anything from Tut's tomb, but offer this drawer from a 'country' Sheraton 1 drawer stand circa 1800. I've indicated the wear lines in the drawer side where the drawer or the opening has indeed slowly deformed over time and rubbing has worn tracks in the wood. On high end work you will see these wear lines uniformly across the width, indicating how precisely the drawer was made. Yes, the drawer still works well although it doesn't exhibit the piston business since the underside of the stand is open.

Ed

Re: each piece shipped with a well tuned plane

Dan Donaldson

>This is anecdotal, but I seem to remember reading one time about students that had to present a piece for their final exam with tight drawers like that. They tried to figure out what the conditions would be on the day they had to present, and then adjust right up until the time they went before the panel. I also remember reading that most of these projects got put away, and that some time later, the drawers were not functional, depending on the season.

Re: each piece shipped with a well tuned plane

Dan Clermont in Burnaby

>Hi Bill,

Dunno how long piston fit drawers have been around but I believe Rob learnt this technique from Allan Peter's.

If your climate is dry right now make them a tad loose and so they don't bind. When the weather gets wet and the drawer expands adjust it if necessary. if the chest of drawers is for somebody else I say try your best to make it tight keeping in mind the easonal changes

I still think the best approach is to use quarter sawn stock to prevent cupping and other movement which may create problems.

Good Luck with it and please keep us posted

Dan Clermont

Regional differences

Bill Houghton, sunny yahoo! in Sebastopol, CA

>I'd like to point out to anyone who's newish to mangling wood and who lives somewhere other than the snow belt that wood swelling and shrinkage seasons vary in different parts of the country. Here on California's north coast, things swell in the winter, not the summer, because the frequent (sometimes constant, especially this year) rain leads to high moisture in the wet season. In summer, as I learned when doing the porch project a couple of years ago, you can bring wood down to 6% moisture content just by putting it in a well-ventilated attic for a month or so.

Re: each piece shipped with a well tuned plane

ThomD

>I think that there are drawers that do the piston thing on furniture I have examines, the question is whether that is .002". I don't think it is that difficult to do you just trim the pieces to the carcass opening, and keep the dovetails to the part thickness.

Peters wrote about this kind of fitting in FWW #73, back in '88. Rob worked at Peters' shop when he was doing his tour of influential shops fo his CV.

Krenov writes about it, and while he is modern in a sense, like Peters' he is traditionally based. They have pretty much oppositte approaches, which shows how difficult it is to get a consistant story wheter form Egypt or the present day. However they are talking about a tight fit.

The whole deal with cabinets is to set the pieces up so that the expansion and contraction is limited to what the wood in the component section will do, and not the whole width of a drawer. In other words X% of the drawer side, and much of the side is not stiff enough to mater. And that piece of wood will be selected for species and grain orientation. Same deal with frames, or solid components.

"Piston thing"

VTAndy

>I'm new to this so please bear with me!

When posters have refered to the drawing "doing the piston thing" and "piston fit drawers," is "piston fitting" a technical term that has been around for some time, or is it a new term? Is "doing the piston thing" when a drawer fits really tightly or is it something else?

I'd like to see the Rob Cosman video.

Andy

Re: "Piston thing"

ThomD

>It refers to a drawer that opens and closes on a cushion of air.

Re: "Piston thing"

ThomD

>I should have possibly said "against" a cushion of air. You feel a little suction or compression of air when opening or closing the drawer.

That could be a 50lb drawer

Jim in Burlington On

>By time you fill that drawer it could weigh 50 lbs. I bought the video talked to Rob about it and think it's a great idea for smaller drawers. I doubt that theory works all that well in Damp old England. Personally on a big drawer like that it would be getting drawer slides. Anyone ever curse a big sticky drawer in a dresser?

Re: That could be a 50lb drawer

Paul Kierstead

> I doubt that theory works all that well in Damp old England.

So long as the drawers were made on one of those very damp days, I don't see why not. Or the construction allowed for those damp days.

Anyone ever curse a big sticky drawer in a dresser?

I have cursed an awful lot of them that racked and stuck because they were too loose.

Boys this aint new!

Rob Cosman

>Gentlemen and Ladies please allow me to address this topic. This is not new, foreign to some but certainly not new. Of the furniture built yesterday and today the percentage made to the standards spoken about would be miniscule. I have not invented anything in this video, merely attempting to bring to the masses what Alan Peters and a few like him have been doing in thier shops for decades. Alan spent 7 years in the Barnsley workshops where this drawer building process was and had been the standard for decades.

Built properly the only expansion you need to worry about is width of the drawer side to the height of the opening. I have hundreds of drawers in customers homes and in my own home, the only adjustments ever needed were made to the top edge of the drawer side, never the face side. Done properly there should be no detectable side to side play, not sure where the .002 measurement came from, it was not mentioned in my dvd. Someone made the comment about accuracy in the case and that is my opening statement in the dvd. The drawer can only be as good as the case. The largest drawer I can recall making was somewhere around 36" by 10" by 24" deep. Standards are the same, though smaller drawers are easier to make and fit but I think this has more to do with the sheer size than anything else. I am teaching two drawer making workshops this summer so we will see how practical this theory is with 24 amatuer woodworkers, some are frequent posters on this forum so I will let them tell you.

For those not convinced I will add this final bit, Alan Peters' furniture is flawless, not only to the untrained eye but to the trained eye. Should you ever be lucky enough to examine a piece I promise you it will reestablish your defination of exact. Quite humbling. I have been lucky to have worked with and examined the furniture of many world renowned craftsman, in my opinion a few come close but no one equaled Alans. So until you have seen this kind of craftsmanship it can be hard to grasp what can be done and in this case what has been done. I thought my work was good, I was humbled. Here is a plug you can take or leave, I hired a crew from London last spring and shot a video in Alans shop. I wanted a record of who this man was and at least a bit of what he has accomplished. His health has been an serious issue for the past several years as you will detect in the video never the less it provides at least a glimpse of the man and his work. Cheers

Rob

ps Pistons need rings to get this kind of fit :)!

From krenov, perhaps..?

Jonathan Kaplan (OR)

>Hi Dan,

I think you are remembering that from one of Krenov's books -- he talks about the 'final' pieces that apprenctices did that were so 'tight' that when you put one drawer in, the others were supposed to 'puff' out a bit; and he mentioned that most of these peices were unusable because the tolerances were so tight that they wouldn't open most of the year.

And yet he also talks about drawers fitting "properly" which sometimes sounds like a kind of 'piston' thing -- the 'tightness' in the back of the drawer that makes it 'pause' before coming out... So it is hard to say, as Dan C. notes below, just what his view of this is...

In any event, it makes sense to me that smaller drawers have closer tolerances -- just in terms of looks that feels right. Of course, the final tolerances of my drawers have more to do with my limited abilities than anything else, but that's just me. :)

jk

Re: Boys this aint new!

Paul Kierstead

>I was just gonna say, I went back and reviewed the DVD, no 0.002" mentioned there; you say the sides should contact and the top should allow for some seasonal movement.

No ...,

Scott Burr in we saw sun Ben Lomond,CA

>The eariler pic of my saw till drawers were made that way. I ended up drilling a 1/4" hole in the back panel so they could actually close with out wating...

Hi Rob, I owe you an apology

HC Sakman @ Victoria, BC

>You're, of course right about what you said in your post. Drawer width has pretty much nothing to do with seasonal movement. My topic is kind of unrelated to the piston fit directly, but related to your video.

Thank you for acknowledging my point in your private e-mail. My apology is about "crediting a specific technique to somebody". I indeed agree that, like you said, (as well as some others) when someone introduces a not-so-well known technique by some means of media, it's only natural that technique will be called whatever the author calls it. (or it'll be named after the author.)

So, as you know already, I was not questioning the credibility of Adam Peters or anybody else in your DVD. I think everything got started when Derek called this (rabbeting tailboard) technique by name and I thought that did not sound right. As I reconsidered my thoughts, it's only natural that a technique is called by whom you heard it from.

I watched your "piston fit" DVD. It's indeed packed with full of neat tricks and wisdom. It's an essential learning tool for the beginners and some who might think they're well seasoned. You're a great teacher/craftsman par excellence and one heck of a salesman! ;-)

Chico...

Re: Cosman "piston fit drawer", a good idea?

Pam Niedermayer - Austin, TX

>I don't even like piston fit drawers, very obnoxious in use; however, although LN sells this dvd as piston fit drawers, Rob doesn't make piston fit drawers in the video.

Pam