# Blum Tandem Drawer Slides Instructions hard to read?!



## dohertycarpentry (24 Jan 2021)

Does anyone have a decent set of instructions of how to make drawers and install slides for the blum tandem concealed slides? I find the website hard to navigate and find simple information.


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## Woodypk (3 Feb 2021)

Doherty...

I've used these slides only once before and as I believe it...

... on the basis you're using a material thickness of 17-19mm

1) Measure cabinet internals lets say.... 710mm , deduct 49mm. - This is the width of the inside of your drawer box. So say you used 18mm material to construct the drawer box, the overall width would be 661mm+ 18mm per side thickness = 697mm overall draw box width

2) depth is measured by the Nominal length of the drawer runners -10mm. So if you buy a 350mm drawer runners, the overall depth of the drawer box should be made at 340mm measuring outside to outside of the box (not including drawer front if the drawers aren't flush mounted with reference to the sides of the cabinet where the runners will be installed. If they are flush mounted against the sides, you need to deduct the thickness of the drawer fronts.

3) the recess of the drawer bottom measured from the bottom of the drawer box sides, to the bottom face of the drawer box bottom should be 11-13mm. So stick with 12mm to make it easy.

4) Now... the bottom face of the drawer box bottom needs to be a minimum of 27.5mm off the bottom of the base of the inside of the cabinet. This would make the scribe line where your screw fixings to mount the hinges to the sides of the cabinet bet 37mm from the base. So.... for ease of fitting, if you scribe a line 40mm from the base of your cabinet, along the length of the side wall where the runners will screw to, this will allow you the 27.5mm minimum + a 3mm extra gap. This will give you the extra room needed if you decide to use the tip-on runners... if not, doesn't matter anyway.

5) before fitting, if you made the drawer box to the sizes mentioned above, you'll have to notch out a 33mm wide notch, from the bottom of the drawer box back, with the notch being 12mm deep - notched depth to the bottom of the drawer box bottom. Do this both sides

6) drill the hole as per the drawings you'll find online... 11mm up from the notch, and 7mm in from the inside of the side panel. If you used 18mm material like the example, this hole would end up being 18mm ( drawer box side material thickness) + 7mm from the panel side = 25mm total from the OUTSIDE of the drawer box. Do this both sides

7) Drill the holes on the front underside of the drawer box (opposite the notch) with the locking mechanism 55mm in from the inside of the drawer panel. Do this both sides

8) Scribe lines and mount the bottom runner.

9) mount further runners remembering that as these are undermounted runners the the runner bottom needs clearance. Eg. if your drawer box sides were 140mm high, and the first line was scribed on the side of the cabinet wall, 40mm from the cabinet base, the next one would need to be marked at 165.5mm up from the fist line at a MINIMUM.

To work it out for your own drawer box side height, do the following..... Assuming you've set the recess of the drawer box bottom 12mm up from the bottom of the drawer box sides, this formula will work. - First scribed line for runners is at 40mm so take your drawer box height EG 140mm -21.5 which is the distance from the bottom of the drawer box sides to the screw hole centre. Then add 10mm clearance (minimum as stated in the manual is 7mm so add 3mm for good measure) then add 37mm which is the distance from the bottom of the runner mechanism to the centre of the screw holes. and draw in your next line.

SO... in summary. (Drawer box side height - 21.5mm) + (10mm+37mm) = spacing between the first scribed line and the second scribed line. MINIMUM.

Remember, this doesn't take into account the drawer front design. There will be a built in overhang allowance for the drawer fronts in this measurement due to the space needed between the drawer boxes to fit the runners as they are undermounted.

The best way to go about spacing the drawers, is the make the boxes with the measurement explained above in step 1-7 and then decide yourself how far apart you'd like you spacings to be depending on how many drawers you're fitting in the cabinet.

... and wow. This is so hard to explain without a drawing...

If anyone knows this system better than I do (doesn't take much) please correct me and set this guy straight.

This is just the way I worked it out when I designed my drawers in CAD and making sure I gave myself a few MM here and there for breathing room.



Tom


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## Woodypk (3 Feb 2021)

Additionally, the measurements I gave will obviously alter depending on the width of your cabinet. But the formulas are the same, the numbers are just examples. 

These measurements must not change:

Cabinet width -* 49mm* = drawer box inside diameter

Nominal length of drawer slide - *10mm* = drawer box depth

Cabinet internal depth + *3mm* = maximum drawer slider length you can fit in the cabinet

Recess height from bottom of drawer box sides to bottom of drawer box height = *11mm MIN* *13mm MAX* - why not stick with 12mm?

First marked line from base of cabinet for lowest drawer = 40mm (strictly can be as 37mm MIN but I like to give a little extra room.)

Distance between scribed line = drawer box height + 25.5mm *MINIMUM*


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