http://festoolownersgroup.com/other-tools-accessories/new-product-veritas-planing-stops-for-yourmft/
Introduction
This report is loosely organized in sections, and covers a lot of territory. The “voice” changes from
section to section, for clarity – but also to allow for my own editorial comment. We’ve had several
people working on the production of data, drawings and photo’s for the last few days and they’ve done
a remarkable job. The word’s below are primarily mine – so if you find any sort of error or quibble – I’ll
take ownership of it.
One of the “unseen” elements in much of this discussion (which I guess I’m now addressing here) is the
inevitable comparison with other products – QWAS, PARF, Festool etc. I would like to make it very clear
that each of these products are excellent alternatives to what we have chosen to do (which of course, is
something different) – and each expresses a different design intent, and offers real utility to any number
of customers. Aside from Festool components (we are a dealer after all) we have no examples of any
other product, and cannot comment on their measurements, tolerances, or performance.
Rob Lee
President, Veritas Tools Inc.
25 April 2013
Background:
We have a tremendous amount of experience in designing and manufacturing bench accessories, and
work holding products in general. As amateur woodworking in North America uses primarily Imperial
measure, most of our products have been built for use with ¾” holes. Recently, we began to produce
accessories to be used in the Festool MFT, as well as metric based benches, many of which incorporate
20mm dog holes. Our MFT clamping kit was designed for positioning and holding work, both on an MFT,
and on any user-made work-surface that uses 20mm holes (which is one reason we supply a bit with the
set). It has been designed to complement the tools offered by Festool, while staying consistent with the
implicit methods of work – extending the features/flexibility of what Festool has developed. We also
have to ensure our accessories that are backward- and forward-compatible with existing and future
Festool elements (tough to guess at that last one), as well as other 20mm devices.
Having designed and produced our own matrix-based clamping solution for more than 13 years now, we
have a considerable amount of experience with these types of products. Sometimes – having a lot of
experience makes it easy to miss explaining some design intent, and design choices.
The Problem – “What we've got here is failure to communicate”
– Cool Hand Luke, 1967
Right up front, and before we get to conclusions, discussion, and data – we (I) will accept that we have
made a number of mis-steps in how we have released this product. There are explanations for each –
but ultimately – it’s our fault, and we will learn from it.
1) We pushed the release - As I noted in my FOG post of March 27th, while the product was ready
to go, we were still producing and releasing internal information. Generally – we do preproduction releases to fine-tune presentation and communication. In this case – we decided to
release early to a wider group of knowledgeable customers (you guys and gals), as customers
were already starting to consider re-purposing Imperial sized product (which was available)
before we could supply the metric product. You were keen to have it – and we were keen to
ship it.
2) We have not completed an instruction manual – As a byproduct of not planning the release, we
released without full instructions, and explanations. Normally, much of this detail is developed
and produced to support the release of individual products, and we released the sets first.
Absent information to the contrary, users made a number of assumptions about the system, the
components, and their use.
3) We did not implicitly guide customers to set reasonable expectations. – Our model has always
been to set an expectation, and exceed it. We strive to always deliver the context and scope of a
product as part of the marketing message. That way – you know what you’re getting when you
order it. That was not the case here. Your expectation of what a “dog” is in the Festool-MFT
context is completely different from the “dogs” in the hand wood working world. We did not
recognize and deal with that.
From the lengthy discussion on the board at www.festoolownersgroup.com , and various
emails/messages I have received, here are what I’ve heard the “issues” to be:
1)
2)
3)
4)
5)
Root diameter of dogs (“loose feel”)
Tolerances on root diameter
Lock knobs on pins, tilting… (bearing surface)
Using Bessey clamps without lock knob.
Waiting for a “perfect fit”
I will address each, but closer to the end of the report, once we’ve covered more background on the
design and development of the system, and had some discussion of the measurements and testing
(don’t cheat by skipping ahead!) .
The System
Now we jump back in time to early 2012, when we were conceptualizing the clamping system. Part of
any R&D project here is the development and discussion of a product brief. Below are two which you
can see for yourself (slightly edited for confidentiality, over-typed in yellow) .
http://www.leevalley.com/home/temprl/Breif1008.doc
http://www.leevalley.com/home/temprl/Breif1008dogs.doc
The ultimate goal of the system as designed was to extend the clamping, work holding, and work
positioning capabilities of the MFT and, for customers without an MFT, provide a way to use many of
the same components. Additionally, we wanted to provide some new work holding options that
complement the use of the MFT for site work. Since the system would be marketed in a Systainer, not
only did the products inside have to be portable, they had to be products the user would want to haul
along.
Here is a more detailed discussion of each of the elements, and the rationale for including them into the
system
Surface dogs
These precision turned on head and shaft diameters for concentricity. Two head diameters. The
dogs can also be used as locator pins for jig boards, or custom dogs fences with the appropriate
sized holes (25 or 30mm). They have threaded bottom holes to lock the dog to prevent rotation,
or to hold the dog in place while transporting the MFT. In normal use – no clamp knob is
needed. Use wide heads for setting fences – you can then still use the locating holes with the
smaller head dogs, with no interference. Note that registration for fence setting purposes
should be done on the turned part of the head only – do not use the milled flat face. Flat faces
provide extra surface contact area for clamping thin material. Compatible for use with the
Festool clamping knobs. Materials – aluminum – avoids damage, keeps the weight down for
portability. Priced economically, they can be recycled if damaged, at minimal cost.
Work Stops
Initially developed as planning stops for hand woodworkers, we have changed the name for the
MFT system, as the MFT (as a standalone work surface) is not optimally rigid for planning. The
main advantage the work stops have is their low profile, and the ability to span the gaps
between system holes, allowing users to register material less than 96mm wide (hole spacing)
against a fence. Low profile keeps the stop away from sanders for all but the thinnest material.
Surface Clamp
A flexible hold-down clamp that can be used in any 20mm hole, on any surface, in any
orientation, as long as it’s at least 5/8” deep. The clamp arm (which slides easily on the post
when tilted, but locks at 90°) has a 2-1/8" throat depth and can grip anything from veneer to
material up to 3-3/4" thick (3-1/8" when the post collar is used as a depth limiter). Anchor
wedging is controlled by the brass knob on the post and clamping force by the knob at the arm
tip. Used horizontally, the post collar acts as a material support. Used vertically, the collar is a
rub ring that protects workpieces from accidental damage by the post rings. Precision machined
from brass, steel and anodized aluminum.
Bessey® Auto-Adjust Toggle Clamps
To eliminate the need for frequent adjustment, these toggle clamps from Bessey are designed
to automatically accommodate material thickness changes of up to 1”, without altering the
clamping force. The high-profile and low-profile horizontal clamps have capacities of 2-3/4” and
2” thick respectively; the in-line clamp has a center height of 7/8” and a 1” throw. Each has a
knurled screw to adjust the clamping force to a maximum of 550 lb. The clamps are 0.100” (just
over 3/32”) thick plated steel with generously sized handles for easy operation. The swivel feet
have non-marring caps. Convenient and versatile, these clamps expedite production and jig and
fixture work. The mounting plate, available separately or paired with a clamp, lets you easily
position the clamp in the dog holes of the Festool MFT/3 multifunction table instead of
permanently attaching it to a surface. The 20mm diameter post on the plate is 11/16” long, just
less than the table top’s ¾” thickness. To secure the plate, it is threaded internally for use with
an MFT accessory clamping knob. The thickness of the aluminum plate adds 3/8” to the
maximum capacity of the horizontal clamps, but doesn’t affect their minimum; you can still
adjust the clamps to hold materials as thin as a sheet of paper against a surface. The center
height of the in-line clamp is increased to 1-1/4”.
Forstner Bit
Designed by Lee Valley, our 20mm of high-speed steel forstner bit is 3-1/2” long overall, with a
3/8” diameter shank.
Economy Clamping Knob
Partner agreements preclude us from shipping Festool components across borders, so we’ve
sourced an inexpensive knob is used for securing our toggle clamp plates and surface dogs
through dog holes in ¾” thick material. The 1-5/8” diameter star-shaped knob is easy to turn.
With a M8 x 1.25 thread, it is also compatible with any Festool accessory that uses a clamping
knob.
Systainer liner
Using a two-tone foam give you immediate visual confirmation that a part has been left behind,
or has grown legs. Kind of a fingerless counting system for careless carpenters . Also designed
to hold the Festool Clamping knobs I don’t use with my Festool clamping elements.
Black/Yellow Systainer
Besides being cool, you can tell right away that it’s got our stuff inside!
Testing Measurement Methodology
In an initial response to a post April 27th I wrote the following:
“Yes - we designed the dogs for a looser fit than others have...based on feedback we had from
several testers, with varying ages of MFT's.
There will always be a degree of variability in hole diameters of the MFT table - yet the
placement of holes should be accurate from a CNC router/mill that made them, so the
positioning of the hole matrix is the "precision" inherent in the system, and not necessarily the
hole diameter.
Dogs will still register on the sides of the holes, no matter what the clearance is.... and
precision is preserved. Now - if the user has to modify the hole diameter for dogs that are too
snug - then inaccuracy is actually introduced to the table surface... it is difficult for a user to
precisely (and concentrically) ream all table holes by the same amount. So - a bit of a double
edged sword here - we can make them as snug as we want - but it will not add accuracy...
It has concerned me to read where people have had to modify MFT holes to get accessories to
fit - and we sure want to avoid that. We recognize the utility of the precision matrix afforded
by the table surface, and wanted to respect that - which is one reason we have no "toothed"
shaft accessories for the MFT, as we do for regular benches (like the Bessey plates).... we
don't want to wear the sides of the holes.
Then too, we want to ensure forward compatibility with other possible Festool items - and did
not want to vary significantly from what Festool themselves do on similar products. “
Of course, we don’t expect everybody to take those statements at face value, and said we would back
up our assertions with data.
Here’s what we did:
1) A brand new MFT surface was taken from stock
2) In order to fit on our CMM (coordinate measuring machine). We cut the surface into two equal
size pieces, with the cut line parallel to the axis the saw would run along. We had to “waste” one
row of holes (a vertical row – parallel to the cut line) as the second piece would not otherwise fit
on the CMM
3) Each piece has two datum pins installed, to provide an absolute reference for the orientation of
the piece. The piece was bolted to the CMM table to ensure it did not move during
measurement)
4) Hole diameters were measured and entered on a spreadsheet (multiple measurements on the
perimeter of each hole define the center, and diameter)
5) Hole location deviation from a common axis was measured (perpendicular and parallel to the
axis of saw travel)
6) Angular variance from 90 and 45 degrees to a chosen line of holes, using different hole pairs,
was measured
7) Measurements for angular accuracy (based on hole pairs) was measured for different diameters
of dogs, and dogs with differences in diameters
8) Direct measurement for each surface section (two sections per piece) were plotted and detailed
on PDF’s
9) Relative positional data (stitched using fixed reference points) was entered on a spreadsheet
Test Measurements
We took pictures of the test equipment, and testing in progress, that you can see here:
http://www.leevalley.com/home/temprl/CMM1.jpg (Half of a table, showing datum pins, and CMM)
http://www.leevalley.com/home/temprl/CMM2.jpg (Trapping measurements with a probe)
http://www.leevalley.com/home/temprl/dogs.jpg (testing accuracy with dog/pin pairs)
http://www.leevalley.com/home/temprl/angular.jpg (testing angular Accuracy)
A spreadsheet located here (http://www.leevalley.com/home/temprl/MFT_analysis.xlsx ) shows six
separate tabs of test data, organized as follows(use link after each tab if Spreadsheet won’t open):
“Holes Sizes” Tab http://www.leevalley.com/home/temprl/MFT_analysis1.pdf
This tab plots the size of each hole in inches. The size was calculated by taking 8 measurements
of each hole (4 top and 4 bottom).
“ Hole Locations“– Metric” Tab http://www.leevalley.com/home/temprl/MFT_analysis2.pdf
This tab presents a table of the absolute (X,Y) location of the holes and the spacing between a
hole and the adjacent holes, based on the derived center of each hole. The X and Y axes were
defined by the holes 1, 7 and 29 for sheet 1. Hole 1 is co-ordinate (0,0). For sheet one,
cumulative variance from ideal matrix position is shown in column F. On the sheet, the dark cells
represent the holes, the numbers are the distances between holes for that direction. All
dimensions are in mm.
“Angle Tests” tab http://www.leevalley.com/home/temprl/MFT_analysis3.pdf
The top table presents the measurements of the sizes of the dogs tested. We used 5 different pairs
of dogs:
-
The anodized dogs sold in the Veritas MFT Clamping Kit, both small and large heads.
Un-anodized dogs manufactured by Veritas to diameter of 0.782”, both small and large
heads
Precision gauge pins used within our QC group to measure hole diameters
The lower table presents the result of measuring the angles of sets of 3 holes, without dogs and with
the 5 different dogs. We tested both at 90 and 45 degrees to determine the variance created by
using dogs, vs directly measuring the holes. For tests with the dogs, a precision bar was pressed
against the dogs to load them and simulate use before measurements were taken against the head
of the dogs. Note that we observed slightly different numbers each time we measure the dog holes,
yet we used the same holes. These small variations can be attributed to measuring the inside of a
hole drilled in MDF, which is an inherently rough surface.
“Angular Variance Table” Tab http://www.leevalley.com/home/temprl/MFT_analysis4.pdf
This is a good one to hang onto. It is a derived table of accuracy implicit for two perpendicular
axes, given a variance in thousands, expressed a given distance from the baseline. In essence – it
says that for a given variance (like a pin variance, hole diameter, or hole location) – the resulting
angular deviation diminishes the farther away you are from an axis. So – a 4.2 thou variation
(which is large!) between pin placements taken 7 holes apart results in an angular error of one
one-hundredth of a degree. Much better than wood movement!
“ Horizontal Alignment” Tab http://www.leevalley.com/home/temprl/MFT_analysis5.pdf
This tab presents the variation of each center point in inches off a horizontal line between the
left and right holes on each row (note “rows” are vertical on the spreadsheet – perpendicular to
the saw cut). Negative numbers are below the horizontal line, positive are above.
“Vertical Alignment” Tab http://www.leevalley.com/home/temprl/MFT_analysis6.pdf
This tab presents the variation of each center point in inches off a horizontal line between the
top and bottom holes on each column (note “columns” are horizontal on the spreadsheet –
parallel to the saw cut).. Negative numbers are to the left of vertical, positive are to the right.
Data for the above are also graphically represented on PDF files below:
http://www.leevalley.com/home/temprl/mft1s1.pdf (side 1, hole location)
http://www.leevalley.com/home/temprl/mft1s2.pdf (side 1, hole spacing)
http://www.leevalley.com/home/temprl/mft2s1.pdf (side 2, hole location, angular accuracy
using given hole)
http://www.leevalley.com/home/temprl/mft2s2.pdf (side 2, calculated angular accuracy)
http://www.leevalley.com/home/temprl/mft2s3.pdf (side two hole location)
http://www.leevalley.com/home/temprl/mftholesdogs.pdf (angular accuracy by dog pair)
A further spreadsheet here shows manual measurements taken from three older (1 ½ years) MFT’s we
had in various departments here. Measurements were taken with precision machine shop gauges.
http://www.leevalley.com/home/temprl/OLD_MFT.xls
If above doesn’t work, use http://www.leevalley.com/home/temprl/OLD_MFT.pdf
Our Conclusions from measurements
Ideally – we’d like all of you to take these at face value – but it’s not realistic that you’ll all do so, and
that’s OK too… but please keep reading!
1)
2)
3)
4)
5)
6)
Registration accuracy is NOT dependent on pin size*
Registration accuracy is dependent on pin/head tolerances
Registration is dependent on hole location accuracy
Registration is dependent on hole diameter tolerances
Registration accuracy is dependent on pin spacing
Festool does an excellent job of maintaining hole locus relative to vertical and horizontal axes,
even if axis spacing varies
‘*’ - Note that we have only tested pins within 5% or so of nominal hole size.
So – the upshot here is that any pair of precision machined dogs will register as accurately as any other
equally precision machined dogs when used in the same holes, no matter what the root diameter of the
pin is. Essential, the “tightness” of the pin is irrelevant, and has no bearing on registration accuracy.
Surprises
During the course of this measurement, we discovered a few things we had not expected to find.
1) Kudos to Festool - The MDF FMT surface is accurate to a surprising degree (for something not
made of metal). While there is understandable variation among hole diameters, and hole
placements, the overall accuracy of the grid is superb for its size, and material. The overall
accuracy is beyond the capability of most people to reproduce without CNC equipment. A
compelling reason to at least buy the Festool surface, if not an MFT! (PS – we have a good price
on two MFT halves….)
2) Almost didn’t want to print this one…..but our measurements showed that pins that fit loosely
had a tendency to register ever so slightly better than tight fitting pins (but not by an amount as
to make a practical difference). We suspect (but have not tested) that this observed effect could
be due to a) the pin not staying perpendicular to the surface or b) the pin has a higher
probability of picking up any defect present in the hole, and expressing it. Really! Based on only
a few data points, and to only a very small degree. Kinda self-serving conclusion – but it is what
it is.
Answers to “Issues” Raised
1) Root diameter of dogs (“loose feel”)
As we have shown, the root diameters of the dogs are not relevant for their use as registration
pins for setting fences, if they are allowed to move - clamping them down will prevent them
from registering properly. Given the fairly wide variance in hole diameters in newer and older
tables, it is not possible to produce a “one size fits all” solution that fits even all of the holes in a
single table. Then too – we have designed our solution to be useful to people that drill their own
holes in other materials, or that make their own tables. A maximally sized root diameter would
end up being too large for a 20mm hole drilled in a wood surface that expands and shrinks by
any significant amount during the season (even if MDF doesn’t). We need some amount of
clearance to preserve to scope of our solution.
2) Tolerances on root diameter
Our tolerances on turned pins (with head concentricity included) are to given size within
.001”(+-). This is more than sufficient for even setting fences and rails.
3) Lock knobs on pins/tilting… (bearing surface)
Our dogs have been designed to provide maximum bearing surface under clamping load –
particularly the wide head dogs. The actual surfaces that resist movement are more than just
the shaft of dog. Since the flat is milled over the diameter of the shaft, there is a flat area above
the shaft (in the horizontal plane) that engages the material being clamped. Additionally, the flat
area on the underside of the head bears against the MFT surface, also resisting rotation, and
providing additional bearing surface at a significant distance from the axis of rotation (in effect,
a much bigger lever than just the post diameter). Measurement and testing shows this is not an
issue.
4) Using Bessey clamps without lock knob.
This is something we don’t recommend. We are reluctant to create friction on the post to
oppose a lifting force, through some sort of engagement of the hole. We feel it could accelerate
wear, and compromise the system accuracy.
5) Waiting for a “perfect fit dog”
Without producing custom pairs/sets of dogs for each person, this is just not possible to do.
Even were we lucky enough to get an exact fit – it only remains exact until the hole diameter
changes (larger through wear, or smaller through hole distortion). Our position is that some
amount of clearance is absolutely necessary for the system to function in the long term. The
holes are what’s variable over time – and exact fit pins cannot be a long term solution for us.
Don’t agree? Don’t give up reading yet!
Actions
Despite our measurements, testing, and publication of this waaay too long document, there will be a
number of people who still want dogs that fit tightly. We get that…. even if we don’t agree (choice is a
good thing!).
For those that insist that tighter makes “righter” , we’ll run a complete set of 4 wider head dogs with
19.90mm root diameters especially for you, and ship ‘em no charge. They’ll be specially marked, and are
the head diameter we recommend for setting fences and rails (if you don’t know why, you skipped
ahead!). If you just want the updated ones (whatever they end up being), you can do that too.
It won’t be tomorrow though, but I will post an estimate once I let our shop know what we’re doing. In
the mean time you can still set everything you want with the dogs you have… give us a tiny vote of
confidence and try it!
We will be making an engineering change on further production of all sizes of dog (but not the other
accessories) to a somewhat larger root diameter (currently proposed is .780”, or 19.81mm). This will still
not be tight enough for everyone, and has the potential to be too large in some holes in older tables, but
is the limit to which we’re able to compromise, without violating the design of the system, and risking
future issue of compatibility. I will keep the group posted as we evaluate what our change will be.