# Calling BLUM Drawer Slide PhDs



## Lovegasoline (Sep 27, 2009)

I'm completing two kitchen flatware/utensil drawers for a built-in cabinet using Blumotion Tandem slides #563H, 21".

The drawers are 5/8" maple, 3/8" bottoms, with hand cut dovetails and a couple coats of Zinsser Sealcoat. They're ready for General Finishes High Performance Top Coat, Flat, to be sprayed. 

Making the drawers was epic (as is this kitchen renovation they'll join)... it's been _years_ since I've hand cut DTs (and then only just a _very few_) and my first time using Blum drawer slides ... whose measurements were more anal and convoluted than anything in memory for a drawer. Add that to the layout for the DTs and all the hand work and it's hard to imagine the work (errors, and hand wringing) that went into two modest looking drawers. Btw if you carefully look at the nearest drawer corner in the first photo, you'll note that the first full dovetail pin from the bottom is narrower than the rest. I originally planned on making pins thinner then I'd ever made before (combined with _wider_ half pins) but too late and at the moment of truth I discovered to my chagrin that my 1/4" chisel was much too big to chop out the waste of such narrow pins without resorting to convoluted chisel acrobatics. So lacking either a 1/8" chisel or a grinder to reshape my extra 1/4" chisel - and being time pressured in a manner rarely recalled in recent memory - that put the kibosh on the narrow pin plan and replaced it with a to my eyes slightly less elegant 1/4" pin size. That's the rear of the drawer so will never be seen by anyone besides you or I. 

Being a rookie with Blum slides I'm not sure what the real world allowances for tolerances are and where they can be fudged. Unbelievably, after the DT layout and assembly everything came out to a Blum pleasing 64" of an inch. Don't ask me to repeat it. It was a trial by fire and along with consecutive projects represents an improvement in my nascant hand tool skills. The only measurement that's a little off is the depth of the base under the drawer bottom, which is a required 1/2" according to Blum. My drawers have a little extra space at approx 35/64" - 9/16" (approx. 3/64" - 1/16" too deep) a matter solely between my ersatz router table (so called) and Lee Valley's drawer slotting bit and a (perhaps poor) judgement call to trim to fit later. The drawers look eminently presentable though in truth they contain enough errors to make my skin dance and required concerted corrective measures directed by the great Tage Frid overlord with additional all purpose muse juice provided by Charles H. Hayward. 

And now my question:
Should I plane the side bottoms to exactly 1/2" (or alternatively add shims to the drawer bottoms) before I shoot the top coats? Will the increased dimension interfere with the slide functioning? 

Worth mentioning are the half pins at the bottom rear of the drawers, bordered by the notched cutouts. When laying out the drawers I realized those half pins would end up orphaned ... and read online concerns of others using DTs on Blum drawers. Is it good idea to drill and insert a 1/4" (or narrower) diameter dowel up through the orphaned half pins to secure them? 


Also as regards installation: 
The cabinets are built-in and as such they contain no backs, wherefore the wall functions as the back. I've attached a plywood cleat to the wall (old plaster and lathe) and was intending to utilize the Blum metal rear mount brackets screwed to the cleat and screw the front of the slide to the cabinet's face frame. My efforts in exegesis of Blum's obsessive, excessive, and uninterpreted instructions suggests that mounting the slide in this manner allows some modest degree of side-to-side play to permit the slides to self-align themselves. Opposing scholarly commentaries in exegesis of the Blum texts suggest that rear mounted brackets should be shunned, scorned, and in truer form replaced by the introduction of side blocking inside the case flush with the inside edge of the face frame, for a more secure mount. [My case sides are stepped on their interior surface due to my increasing the depth of the cabinets - by extending the 100 year old sides with plywood - thus necessarily complicating the use of side blocking. Further, I doubt the case sides are exactly 90 degrees to either the face frame or wall as everything in this kitchen is old and crooked. Stepped and tapered side blocks anyone?] Rear brackets seem an easier solution. 

Thoughts? 



Oh. I forgot. 
Moby Dick.


This is part of an epic grovel through hell. 
https://www.woodworkingtalk.com/f17/...ertise-200209/

I took a break ...which unexpectedly lasted two years (didn't really have opportunity to make more of a mess or use machines). I had a chance ... and the drive ... to resume so I've been getting the drawers and countertops done ... and if I can manage it, get at least some of the cabinet doors completed. 

Anyone with deep experience regarding cabinet doors, fittings, adjustments, countertops installation, and especially sourcing matching hinges (in both dimension and hole pattern - which has been a complete dead no matter where I've looked, and I've looked long and hard) keep an eye open as I may need to draw on your expertise.


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## GeorgeC (Jul 30, 2008)

Can you summarize exactly what is your question(s)?


George


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## Lovegasoline (Sep 27, 2009)

GeorgeC said:


> Can you summarize exactly what is your question(s)? George


"The only measurement that's a little off is the depth of the base under the drawer bottom, which is a required 1/2" according to Blum. My drawers have a little extra space at approx 35/64" - 9/16" (approx. 3/64" - 1/16" too deep)

...

And now my question:
a.) Should I plane the side bottoms to exactly 1/2" (or alternatively add shims to the drawer bottoms) before I shoot the top coats? Will the increased dimension interfere with the slide functioning? 

b.) Worth mentioning are the half pins at the bottom rear of the drawers, bordered by the notched cutouts. When laying out the drawers I realized those half pins would end up orphaned ... and read online concerns of others using DTs on Blum drawers. Is it good idea to drill and insert a 1/4" (or narrower) diameter dowel up through the orphaned half pins to secure them? 

Also as regards installation: 
The cabinets are built-in and as such they contain no backs, wherefore the wall functions as the back. I've attached a plywood cleat to the wall (old plaster and lathe) and was intending to utilize the Blum metal rear mount brackets screwed to the cleat and screw the front of the slide to the cabinet's face frame. My efforts in exegesis of Blum's obsessive, excessive, and uninterpreted instructions suggests that mounting the slide in this manner allows some modest degree of side-to-side play to permit the slides to self-align themselves. 



c.) Opposing scholarly commentaries in exegesis of the Blum texts suggest that rear mounted brackets should be shunned, scorned, and in truer form replaced by the introduction of side blocking inside the case flush with the inside edge of the face frame, for a more secure mount. [My case sides are stepped on their interior surface due to my increasing the depth of the cabinets - by extending the 100 year old sides with plywood - thus necessarily complicating the use of side blocking. Further, I doubt the case sides are exactly 90 degrees to either the face frame or wall as everything in this kitchen is old and crooked. Stepped and tapered side blocks anyone?] Rear brackets seem an easier solution. 

Thoughts?"


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## Lovegasoline (Sep 27, 2009)

Bump.

All issues resolved except for following:

Drawers are built to Blum's specs to the 64th of an inch; the only measurement that's a little off is the drawer bottom clearance (spacing between drawer bottom and bottom of drawer's sides, front, and back) which is 1/2" according to Blum. 
My drawers have a little extra space measuring 35/64" - 9/16" (approx. 3/64" - 1/16" too deep).

a.) Will the increased dimension interfere with the slide functioning or is there some wiggle here? 
Will I need to plane the side bottoms to_ exactly_ 1/2" (or alternatively add shims to the drawer bottoms to bring the spacing to 1/2")? If yes, I'd like to do it now before drilling the drawers for the locking mechanisms and/or shooting the top coats.

-The drawers are full overlay in a face frame cabinet.
-Blum locking mechanism used is T51-190xx (side-to-side adjustable).


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## J.C. (Jan 20, 2012)

Their clearances are normally pretty forgiving. I think 9/16" will probably be alright but I want to say that's about the limit. I'll take a look tomorrow and see if 9/16" would be a problem.


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## Lovegasoline (Sep 27, 2009)

Thanks a bunch J.C.


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## kwoodhands (May 1, 2020)

The tolerance of 1/2" means that is the least amount of clearance you need. 9/16" is fine .
mike


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## NoThankyou (Mar 21, 2018)

You may have to plane. The issue is that the drawer rests on the slide and you don't want it to drag. If the drawer drags on the slide, the soft close feature will have difficulty.

Go ahead and install the mounting clips on the bottom of the drawers. Snap the drawers in place. See if they work. Plane if you have to.

BTW ~ The Blum drawer slide line has but two critical measurements, depth (front to back) and distance between drawer sides. 

The front to back distance is from the inside of the front to the outside of the back. This precludes any variation of drawer box material. 

The width measurement has a minor complication. There are two models of drawer slides for either 3/4" or 1/2" drawer box material thickness. (I think that the drawer box thickness numbers are correct but it is best to use the Blum documentation for reference.) While you can put a 1/2 box on a 3/4 slide, the reverse is not possible. 

The interior distance between the sides of the box is best about 1/32 more than the distance between the outsides of the drawer slides.

Tip ~ Determine the width of the drawer box after installation of the drawer slides in the cabinet.


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## J.C. (Jan 20, 2012)

There shouldn't be a problem with 9/16 but that is about it. Anymore than that and you run into the pin that engages the soft close mechanism.


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## mmwood_1 (Oct 24, 2007)

NoThankyou said:


> The front to back distance is from the inside of the front to the outside of the back. This precludes any variation of drawer box material.



This was a frustration to me. I figured out a way around it. :wink:


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## Lovegasoline (Sep 27, 2009)

Thanks to everyone for all the input.


Special thanks to you J.C. for checking the actual tolerance.
I'll apply the top coats, install the attachment devices, and complete the install assuming everything will work just fine. If there's an issue I'll plane the bottoms later. 



So it's the little pins with the flat tops that need to be cleared for the slides to function without binding?


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## J.C. (Jan 20, 2012)

The pin actually travels with the drawer so it will only hit when you install the drawer. If you have the slides already, just turn your drawer over, turn one of the slides over and rest it on the drawer to make sure it doesn't bottom out on the pin.


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