MFT/3 replacement top as a ‘template’ (20mm bushing size?)

[Svar]

Think about it...dog hole diameters, aluminum/stainless/delrin (all have different rates of thermal expansion) dog outside diameters along with dog hole locational distances, why would you think that this is in any way a precision guide to cut precise angles?
So remove the dogs and reinsert the dogs 100 times into that CNC machined MFT you had made and the apply pressure from different directions to the dog holes and then simply measure the pattern and you will find out that your perfect MFT is less than perfect.

Seriously, thermal expansion of a 20 mm dog? This is woodworking. I've been using shop made top for referencing and setting angles for years and it works perfect every time.

 

[Cheese]

Seriously, thermal expansion of a 20 mm dog? This is woodworking. I've been using shop made top for referencing and setting angles for years and it works perfect every time.

Just saying...every variable has a potential toll on the final product. So rather than just scratching our heads and conjecturing for days, let's put the facts out front...if you're going to use a questionable MFT for repeatable critical cuts...good luck.

I'd much rather employ jigs, fixtures and hard stops like Kapexes to achieve the critical cuts I need.

Everyone's free to butcher their wood in the manner they choose.  [smile]

 

[Svar]

I'd much rather employ jigs, fixtures and hard stops like Kapexes to achieve the critical cuts I need.

Well, my table IS a jig with hard stops.

 

[AlexThePalex]

I'm currently in the process of doing this and I'm really disappointed by the 20mm Festool router bit. The hole is too big and the 20mm bench dogs is moving inside the hole.

Which Festool bit did you use? You get the best holes with a spiral upcut bit but I am not sure Festool has one. Festool's 20 mm hinge boring bit is made for shallow holes of 10 mm and does not have the precision required for dog holes, and their standard 20 mm bits are made for dados and are not really suited for plunge cutting.

 

[Michael Kellough]

Other than it’s intended purpose, the Festool 20mm hinge boring bit is only good for making holes for clamps to pass through. Unless able to make your own custom sized dogs.

 

[Svar]

There are few discussions regarding different 20mm boring bits on FOG. For example:
https://www.festoolownersgroup.com/festool-how-to/20mm-plunge-bit/msg443863/#msg443863
https://www.festoolownersgroup.com/...ncements/mft-jigtemplate/msg535302/#msg535302

Bottom line - it's a hit and miss.

 

[Francis_Beland]

I'm currently in the process of doing this and I'm really disappointed by the 20mm Festool router bit. The hole is too big and the 20mm bench dogs is moving inside the hole.

Which Festool bit did you use? You get the best holes with a spiral upcut bit but I am not sure Festool has one. Festool's 20 mm hinge boring bit is made for shallow holes of 10 mm and does not have the precision required for dog holes, and their standard 20 mm bits are made for dados and are not really suited for plunge cutting.

I'm using the 20mm boring bit (491072). Is there another bit that can do this since the plunge router is the best way to ensure a 90 degrees plunge?

 

[sandy]

Festool 491072 is the one that I use, without any problems.  Are you sure that’s the issue, and that it isn’t the dogs?  Have you measured their diameter with a micrometer?

Sandy

 

[Francis_Beland]

Festool 491072 is the one that I use, without any problems.  Are you sure the issue issue, and that it isn’t the dogs?  Have you measured their diameter with a micrometer?

Sandy

The dogs are Precision dogs. When I measure the hole drilled with the bit, it's at 20,4mm. If I remember correctly, the dogs are 19,95mm.

 

[sandy]

The dogs are Precision dogs. When I measure the hole drilled with the bit, it's at 20,4mm. If I remember

It sounds like either the bit is oversized or it was not plunged vertically.  If it’s the bit, I’d return it, and I’d check it’s replacement.  As I said, I’ve had very good results with the Festool 20 mm bit in my OF 1400 using the LR-32 system.

Sandy

 

[ChuckM]

Seriously, thermal expansion of a 20 mm dog? This is woodworking. I've been using shop made top for referencing and setting angles for years and it works perfect every time.

Just saying...every variable has a potential toll on the final product. So rather than just scratching our heads and conjecturing for days, let's put the facts out front...if you're going to use a questionable MFT for repeatable critical cuts...good luck.

I'd much rather employ jigs, fixtures and hard stops like Kapexes to achieve the critical cuts I need.

Everyone's free to butcher their wood in the manner they choose.  [smile]

I'm on the same page as yours that the result of replicating a CNC produced MFT top with templates, router bits and drills can be close but not guaranteed.

Of course, for woodworking purposes, the close-enough result may be good enough for the DIY makers of the tops. Many woodworking projects including commercial productions, especially larger ones, are not finished dead square and/or straight.

 

[Francis_Beland]

Thank you for your reply. Thinking about it, I need to put the bit quite high on the collet to be able to plunge all the way down. It's maybe the reason why the hole is larger. I'll do more tests and I'll report back.

 

[sandy]

Thank you for your reply. Thinking about it, I need to put the bit quite high on the collet to be able to plunge all the way down. It's maybe the reason why the hole is larger. I'll do more tests and I'll report back.

Interesting... As I use the LR32 system with the 20 mm router bit, the tip of my bit starts out at the surface of the new top, so I hadn't considered that you were, first, plunging through an existing 18 mm "template" before even reaching the new top.  You need to remember that any angular variance in verticality is greatly amplified by the distance that the variance is displaced.  A minuscule misalignment of the bit in the collet can make a large difference by the time you've plunged the bit 36 mm though the template and the new top.  Of course, any misalignment from vertical will elongate the circular hole from the nominal 20 mm of the bit diameter.

Sandy

 

[Cheese]

I'm using the 20mm boring bit (491072). Is there another bit that can do this since the plunge router is the best way to ensure a 90 degrees plunge?

I made an MFT from 18 mm Baltic birch using the Festool 491072 router bit. The results were excellent and consistent. At the time, I measured 20 of the the Festool made holes in 2 directions, vertically and 90º to vertical because I was having issues with the Woodpeckers MFT jig while using a Whiteside 1/2" diameter spiral router bit.

The Festool machined holes averaged 20.23 mm in one direction and 20.18 mm at 90º to the first measurement. The Festool 491072 bit measures 20.10 in one direction and across the spurs it measures 20.14 mm.

So, averaging all 20 of the Festool machined holes that were measured in 2 directions, the Festool made holes averaged out to be 20.21 mm in diameter.

I use Woodpeckers dogs because they range from 19.90 to 20.20 mm in diameter.

Measure your Festool bit as the 20.40 mm holes seem quite large for a 20.14 sized bit. All router bits will cut slightly oversize but not that much oversize.

 

[Stone Message]

I would like to explain why I created the "Parf" collection of products but am not in any way trying to promote them when there are excellent products available from QWAS, Festool and Lee Valley.

When I created the original Parf Dogs, made and marketed by Lee Valley under their Veritas range, the diameter of the dogs had to be a complete compromise. There were several different "20 mm" hole sizes on Festool products, there were many other holey benches on the market. A best fit size was established thanks to the ingenuity of the Lee Valley team. Those original Parf Dogs were marketed without any control or even influence on the various manufacturers of the products that they were destined to be used with.

After a while I decided that it would be better to create a "family" of products that eliminated some of the guesswork and where the dog sizing and hole sizing were unified. The Parf Guide System and all of the associated Parf Dogs (the originals from Lee Valley and the subsequent designs that I have created under the UJK label) would then work together. The aim has been to eliminate any compatibility issues associated with products created by so many different manufacturers.

For some woodworkers the ultimate precision that the Parf products support is not an issue. As I said before, there are some great products from QWAS and others (there are also so blatant copies of my designs but so be it). But my aim was to bring everything together to help eliminate compatibility (sizing) issues.

Peter

 

[Jerry Ostashevskyi]

Before making an MFT replica one should decide whether the holes will be used for indexing or as clamping/workholding holes only. If second is your answer, simply take a ruler and a square triangle, mark approximate holes and use a router with a 20mm boring bit. It will satisfy the purpose fully.

For indexing, it's obviously different.

Contacting your local CNC shop to manufacture a tabletop is the best solution.

Second best will be using the largest template possible. MFT/3 table top will work great for that because it has been made on a CNC. As it was pointed, MFT tops can vary in hole diameter, but not within one tabletop. When deciding upon the diameter of our Precision Dogs, I have visited multiple dealers in the area and took measurements of the holes in over a dozen MFTs. It was done 8 years ago, but I doubt that Festool has walked back on it’s quality control. To support my assumption, we would hear complaints about the fit of our dogs if that would have been the case, and there has been none.

Why use MFT as a template? Simply because of its size. You will have to reposition it the least amount of times and keep a setup error to a minimum. Every time a template is moved, setup error will be accumulated.

Assume you have a 4x3 hole template with a starting point in the bottom left corner going from left to right. Your initial 12 holes will be dead on relative to the origin. When the template is moved, your origin changes ( the last three holes on the right take its place). There is always some play in dogs or pins (if they would be the exact size of the holes, you won’t be able to insert them) which adds an error. Move a template again, error builds up. If one is trying to replicate a MFT tabletop (10x7 holes) with such template, to reach the top right corner template has to be repositioned 7 times, so it will get at a maximum 7x setup error relative to the initial origin(bottom left hole).

A few years back we have done testing when we looked into making our template, and none has produced results which we would be able to call precise, thus defeating the purpose of making it.

Coming back to a large MFT fabrication. To get the best results one will need:

MFT top and a plunge router with dust extraction.
20mm guide bushing for a router base
½” boring bit or a metric equivalent
1” long ¼” flush trim router bit with an upper bearing or a metric equivalent
About 4 clamps to secure table tops to one another.
A couple of dogs that have shaft length longer than original MFT (our Precision Rail dogs with adjustable collars, for example)

To begin with, align the two edges of the MFT with the edges of your future table top and secure it using some clamps. Using a router with a 20mm guide bushing and a boring bit, place it in every hole and plunge it. After every holes has been done. Remove the bushing and swap the boring bit with the flush trim router bit. Plunge the router into a hole made by a boring bit and secure at the required depth. Turn the router on trace MFT hole with an upper bearing. Repeat with every hole.
Next, reposition MFT table top and align holes on the edges of the original MFT with newly made one using Rail dogs. Secure with quick clamps and repeat the above.

Making an MFT top with a “holly” rail, as described above, is a great option too.

I hope this long read will be found helpful

Jerry

 

[sandy]

[member=71502]Jerry Ostashevskyi[/member]

Minor points... MFT/3 table has 11 x 7 hole pattern, and moving a holey rail vs an entire MFT top is not only easier but it is considerably faster, as it does not require repeated plunges or pattern routing steps at each hole.

Of course if an LR32 system is not available, then using an existing MFT top may be the only option.

Sandy

 

[Jerry Ostashevskyi]

[member=71502]Jerry Ostashevskyi[/member]

Minor points... MFT/3 table has 11 x 7 hole pattern, and moving a holey rail vs an entire MFT top is not only easier but it is considerably faster, as it does not require repeated plunges or pattern routing steps at each hole.

Of course if an LR32 system is not available, then using an existing MFT top may be the only option.

Sandy

I stand corrected. Sometimes my mind plays tricks with me  [smile]

Agree on speed with the holey rail too. My concern will be with the boring bit. Claimed 20mm bit size often produces oversized holes (fell victim to that a few times) making multiple accessories available on the market that use them to be loose. So test-test-test

 

[Francis_Beland]

Thank you for your reply. Thinking about it, I need to put the bit quite high on the collet to be able to plunge all the way down. It's maybe the reason why the hole is larger. I'll do more tests and I'll report back.

Interesting... As I use the LR32 system with the 20 mm router bit, the tip of my bit starts out at the surface of the new top, so I hadn't considered that you were, first, plunging through an existing 18 mm "template" before even reaching the new top.  You need to remember that any angular variance in verticality is greatly amplified by the distance that the variance is displaced.  A minuscule misalignment of the bit in the collet can make a large difference by the time you've plunged the bit 36 mm though the template and the new top.  Of course, any misalignment from vertical will elongate the circular hole from the nominal 20 mm of the bit diameter.

Sandy

To give an update, I tried again by installing the bit closer to the collet and the result is almost perfect. In my other setup I was using a 12mm template plus the guide bushing plus the router base plate. I now tried to make a template from 6mm baltic birch screwed on the plunge base (I removed the bottom plate) and now it's working great. I just finished my top. Thank you Sandy for your input.