Hole size for home made MFT

[bdormer]

Hi -

I'm building a workbench and would dearly love to be about to use Clamping Elements on it.  What size (and BRAND) bits are people using to drill holes that the Clamping Elements will fit in?

I have tried:

Rockler 20 mm bit (too big - the clamp lifts way up when it's clamped)

MLCS 20 mm bit (better than the Rockler - but clamp and workpiece still lifts up 1/16 or so)

McMaster-Carr 25/32 bit (On Order - fingers crossed)

FYI - I have a couple Black & Decker Workmates - and the Clamping Elements fit in those pretty well (results were about like the MLCS bit).  Because one of my workmates is an original (1960's - pre-metric-system) I figured 25/32 was worth a shot.

TIA -

 

[The Dude]

Festool Bit 491072.  20mm boring bit w/8mm shank

Timmy

 

[bdormer]

Will that bit give a snug hole so that the Clamping Elements don't lift up when they are engaged?

 

[The Dude]

Will that bit give a snug hole so that the Clamping Elements don't lift up when they are engaged?

The Holes on the MFT are 20mm dead on.  We have several clients that have made their own MONSTER MFT.  This is the bit they used in the OF 1400 to drill the holes for the table...works like a champ!

Tim

 

[Roland Chung]

The Holes on the MFT are 20mm dead on.  We have several clients that have made their own MONSTER MFT.  This is the bit they used in the OF 1400 to drill the holes for the table...works like a champ!

Tim
[/quote]

Tim,
Any chance of getting some images and maybe specs from the guys that made their own?  I always love to see custom MFT's and MFT mods.  There is always something a little bit different - always some thinking just outside the box.  I like everything that I have seen on this forum, but it's been a while since I've some new custom MFT's.

 

[bdormer]

How long is the shank on the 20mm bit?  My bench slabs are 1.5 inches (about 38.1 mm) thick.

Thanks Again!

 

[bdormer]

Found my own answer - the bits are 54.5 mm (2.14 inches) long - should be more than adequate to get thru my bench slabs.

 

[mhch]

For european MFT owners:  20mm electrician PVC pipes make perfect
dogs for the MFT, cheap, easy to make as many as needed, and they
stay in place by friction

 

[dirtydeeds]

for those who dont mind abusing their worktops

a domino makes a very quick bench dog

my mft top gets changed at least once a year

i dont bother with putting the holes in a regular pattern

i just use a 20mm forstner bit into the top, where and when i need one

 

[Dave Ronyak]

How long is the shank on the 20mm bit?  My bench slabs are 1.5 inches (about 38.1 mm) thick.

Thanks Again!

You are likely to have a problem inserting/removing a Festool L-style clamp (some call them F-style clamps) if you use an extra thick top.  The clamp arm has to be inserted through the hole and rotated ninety degrees.  The ninety degree corner together with the thickness of the steel material of the clamp arms will cause the clamp arms and the outside (apex) of the ninety degree bend corner joining the clamp arms will jam against the sides of a 20 mm hole if the thickness is too great. If you are determined to use a thicker top, you could make larger diameter holes but then they wouldn't work with other Festool accessories.  Alternatively, you could slot the holes to provide clearance for the clamp arms.  Someone has posted photos of doing this to enable use of non-Festool clamps with a standard MFT top.  You could also counterbore the extra thick top from the bottom side to provide the necessary clearance for the Festool clamps, and to enable use of standard Festool acessories (mitre fence, clamping elements).

Dave R.
Dave R.

 

[bdormer]

Dave -

I already have some excellent Sjoberg clamps that will work in place of the L-style clamps (and I was aware of the limitation you point out).  What I am really interested in using are the FESTOOL Clamping Elements.  The alternative would be Veritas Wonder Dogs.  The wonder dogs require a lot of screwing the clamp arm in and out.  Clamping Elements are quite simply, the better solution.

I've found that a 25/36 inch drill bit will make a hole that the Clamping Elements will fit in without lifting up when clamped - although it's a pretty tight fit.

I'm going to give the Festool 20mm router bit a try - I'd rather make the 60 or so dog holes I need with a plunge router than a drill anyway. 

 

[Dave Ronyak]

Dave -

I already have some excellent Sjoberg clamps that will work in place of the L-style clamps (and I was aware of the limitation you point out).   What I am really interested in using are the FESTOOL Clamping Elements.  The alternative would be Veritas Wonder Dogs.   The wonder dogs require a lot of screwing the clamp arm in and out.  Clamping Elements are quite simply, the better solution.

I've found that a 25/36 inch drill bit will make a hole that the Clamping Elements will fit in without lifting up when clamped - although it's a pretty tight fit.

I'm going to give the Festool 20mm router bit a try - I'd rather make the 60 or so dog holes I need with a plunge router than a drill anyway. 

The clampimg elements won't lift up at all if you use the supplied threaded knobs to secure them from the underside of the MFT top.  I admit I don't always use those threaded knobs, but I do if I plan to apply a lot of force on the clamping elements.

Dave R.

 

[bdormer]

With a 1 3/4 bench top - the supplied knobs are unusable.  I'm hoping I won't need the knobs at all (and I'm told that if the dog holes are the right size - that will be the case).  Even so - I will probably hunt down some metric screws and make my own knobs for the times when I do need them.

 

[Corwin]

Been checking out those holes a lot the last few days.  Three of my MFTs still wear their original tops.  The oldest is over two now, and has tighter holes than the others.  Holes in this top range from .774" to .785" with most just over .782".  My Clamping Element Holders measure about .785" at a wide point but are a little smaller for the remainder -- and they fit anywhere from just barely snug to so tight I have to struggle to get in or out in this table.  I believe this works fine as the Holders should set centered in these holes.

The other tables have holes that range from .790" to .796" -- most from .790" to .792".  The Clamping Element Holders fit loosely in all of these holes.  Rather that locating at the center of the hole, as they do with my first table, holders placed in these tables align to the side of the holes -- that is if you align them such. 

While the holes may vary slightly in diameter, the important thing is that they do seem to be very accurately located -- the centers appear to be right on the 96mm grid.  This makes for some easy setups -- now that Steve has pointed this out.  But, if your clamping element holders fit loosely in the holes in your table and those holes also vary in diameter, you will be off somewhat.  Best to find a way to take up the slack...

And that's what I've been up to --- tacking up the slack, that is.  Here in the USA it is hard getting a good selection of metric items.  I went to all three hardware stores in town today -- mixed luck, but I did find some short lengths of solid steel rod that measures .790" OD that fit perfect in my newer tables (not a chance with the older one) -- this was some salvaged material I found at a marine hardware store.  Sorry, they no longer have any more. 

 

[mhch]

I use 20mm PVC dogs, cut into 50mm long sections.
They fit perfectly, no wobble, and stay in place by friction.
in my MFT (0.788" holes)  delivered in September 2007.

If you want to give it a try, the url below leads you to a site
site selling 20mm PVC pipes by the meter (1.30 euro
  a meter, about 2 USD) and ships international (21 euros,
  about 20 USD).  Probably worth grouping orders !!!!
http://www.aquasyl.fr/q4/index.php?p=p_91&sName=pvc-tube
   
Don't hesitate to contact me if you need some help with French
to fill forms.

 

[bdormer]

Unless theres a group buy - I was thinking of getting some hardwood and turning it down to 20mm on the lathe.  I was thinking that Purpleheart would be awfully nice looking as a bench dog.  My local supplier/mill shop always has a table full of off-cuts that can be had on-the-cheap.

I've found that my Veritas 3/4 bench pups work fine in 20mm holes.

I also have TONS of Black & Decker Workmate accessories (including bench dogs) that work in 20mm holes.  Apparently, the workmates are drilled to something close to 20 mm.

 

[Dave Ronyak]

With a 1 3/4 bench top - the supplied knobs are unusable.  I'm hoping I won't need the knobs at all (and I'm told that if the dog holes are the right size - that will be the case).  Even so - I will probably hunt down some metric screws and make my own knobs for the times when I do need them.

Unless you counterbore about half way through the thickness of the top from the bottomside.

Dave R.

 

[bdormer]

Right - its a tradeoff - counterbore 60+ dog holes or make 4 knobs.... I think the shorter path is to make the knobs.

 

[mhch]

Unless theres a group buy - I was thinking of getting some hardwood and turning it down to 20mm on the lathe.  I was thinking that Purpleheart would be awfully nice looking as a bench dog.  My local supplier/mill shop always has a table full of off-cuts that can be had on-the-cheap.

I've found that my Veritas 3/4 bench pups work fine in 20mm holes.

I also have TONS of Black & Decker Workmate accessories (including bench dogs) that work in 20mm holes.  Apparently, the workmates are drilled to something close to 20 mm.

A number of the workmate variants have 20 mm holes. I use a Wolfcraft Master 600
as a side table to my MFT and I regularly clamp things in it using the various Festool
clamps, as I mentioned in threadhttp://festoolownersgroup.com/index.php?topic=1719.0

 

[Dave Rudy]

I'd be in for a group buy in France if necessary.  I could even volunteer to go over there as a representative of the group to pick up the pvc and bring it back.  All I'd ask is expenses.

Another thought -- is 20mm pvc available in Canada?  We might give Dan an excuse to contend with American Border Patrol instead of Canadian and cut down on shipping costs. -- and maybe get another border crossing story in the bargain.