Qwas dogs - thickness variations ?

[NuggyBuggy]

I bought a package of 4 Qwas dogs and 2 rail dogs recently, mine are anodized(?) black.

The other day I noticed there was a little play in one of the two I was using, so I tried the other two dogs.  While the first two went in easily (in fact one has a little more play than I would have expected), the latter two are clearly wider - they have difficulty fitting into my MFT/3 holes.  Worse is getting them out - I couldn't pull them out by hand nor push them out from underneath.  I was on a deadline and ended up having to use a vise-grip to extract it (I figured it was better than possibly dimpling them by hitting out from the bottom).  No problems with my rail dogs.

The holes on my top are clear, and I'm testing all the dogs on the same holes.  Moreover, they have the same issues on all the holes I cared to test, so I don't think it's variation in hole size.

Has anyone else noticed substantial size variations in their dogs ?

 

[Brice Burrell]

I haven't had any problems with my Qwas dags.  Might be worth contacting the retailer or Qwas.

 

[NuggyBuggy]

I haven't had any problems with my Qwas dags.  Might be worth contacting the retailer or Qwas.

Thanks Brice.  The retailer I bought my Qwas dogs from doesn't even seem to interested in answering sales queries.  I think I'll see if I can track down a contact email for Qwas or PM him.

 

[peter halle]

I have 4 of the original, 2 rail dogs, 2 rail dogs that I can't talk about, and 2 more experimental dogs that I also can't talk about.  I wish I could talk about the one's I can't.

I have never had an issue with the dogs interface with the MFT/3 until about 3 weeks ago.  Our area has had a ridiculous amount of rain and the accumulating amount of moisture has slowly been effecting the mft top.  The dogs that worked smoothly a month ago now have to forced out.  My dogs are all acting the same way with the exception of two that I can't talk about.  They are gripping even more - but that is a great thing.

Get in contact with Steve.  I only offered the above as a comparison to what I have recently experienced due to weather.

Peter

 

[Brice Burrell]

I haven't had any problems with my Qwas dags.  Might be worth contacting the retailer or Qwas.

Thanks Brice.  The retailer I bought my Qwas dogs from doesn't even seem to interested in answering sales queries.  I think I'll see if I can track down a contact email for Qwas or PM him.

Get in touch with Steve (Qwas), Qwas products.  Scroll down to the bottom of the page for with contact info.

 

[bpitch]

If you have a caliper you can measure the thickness of all dogs and compare them, if a difference is within 0.001-0.002" its a normal margin for CNC production.
In any ways, surely do, contact Qwas.

 

[tallgrass]

I would expect a  +-.001 would be quite a good tolerance and i would not be surprised if it was more. This is not a negitive comment but a reflection of manufacturing and materials envolved. As an ME , accumulated tolerances can be quite a pain and are a  bane of my existence  . Especially with the materials in question, wood will expand and contract with moisture , as we all know,  the thermal coefficient of expansion of aluminum is close to 12(10^-6 in/in degF). Needless ,a friction fit can be tough to maintain accross all tables. I am actually impressed that these dogs work as well as they do. Not to say that your questions and concerens should not be answered, just thought I would chime in.

 

[Harvey]

I checked five power coated Qwas dogs with a dial caliper as bpitch suggested- they were within .02 mm (0.000787 in) of each other.

 

[bpitch]

I checked five power coated Qwas dogs with a dial caliper as bpitch suggested- they were within .02 mm (0.000787 in) of each other.

If measured correctly, such thickness variance is quiet irrelevant for woodworking. A friend of mine is an optical engineer and they design and manufacture microscopes for scanning brain tissue. I remember he told me that when they manufacture parts for their microscopes, the tolerances are 1 mil= 0.001" for the parts...

 

[Qwas]

Nuggy Buggy has contacted me and we are communicating to get answers for me and a happy resolution for Nuggy.  [smile] I've been having some internet issues with my ISP that has kept me from getting on here before this.

For those interested, I try to keep a tolerance of .001" on all the dogs diameters. This is fairly easy to do and is standard tolerances for machining.  Due to the length of the Rail Dog, it can have a taper  but I try to keep the taper under .001" except for the extreme ends (last 1/2") of the Rail Dog where it doesn't matter. The powder coated dogs are harder to keep within the tolerance since the coating can vary in thickness.

I will tell you from my experience, and customer feedback, 1/2 of .001" can make all the difference in the world on how the dogs fit in the holes. That small amount is definitely noticeable to any one using the dogs.

The talk of tolerances comes up often on this forum and I think it needs some clarifying. Hopefully no one here is trying to make a 3 foot square panel and hold it to .005" tolerance, it just can't be done on a repeatable basis. I would think anything beyond 1/64" (.016") is pushing your luck (this is mostly due to the machines we use, not the wood). But if you're making a dado for a panel to fit in, then 1/64" is very loose and most would find unacceptable for gluing. If you were to make a 1/4" bolt hole in the panel, you may not be happy with 1/64" tolerance.

When it comes to tolerance for being square, saying it's out by 1/8" doesn't tell anybody anything. We need a length to go with that 1/8". There's a big difference between being out of square by 1/8 over a 12" length and by 1/8" over an 8 foot length. You should always include a length.

[start rant]
Since World War I (nearly 100 years ago) machinists have understood the need for standards and tolerances. Because of this parts can made in separate parts of the country and still be assembled together with exacting fits. Yet woodworkers continue to buy rulers that are not marked correctly and squares that are not square (would you buy a saw that could not saw???) and it is all done with the excuse that tolerances don't matter with wood because wood moves. That "excuse" should be the exact reason to demand accuracy, not ignore it. Think of all the work that is redone by woodworkers because one guy's ruler was off from the other guys, or something was built to fit a square corner but at install time they discover the corner wasn't square. All of this can easily be stopped by demanding better tolerances from your basic tools.

[end of rant]

 

[rmwarren]

Also, as I think Peter basically pointed out, the tolerance of the MFT holes is far and away worse than that of the dogs. If anything I would think that is the real culprit.

While Festool does a good job overall with the MFT tops I don't think they even pretend that there is a tight tolerance spec, it is mostly a happy accident that they are as accurate as they are and we can make use it that. The MFT was designed with holes for clamps, not precision layouts.

Just my  [2cents]...

RMW

 

[Qwas]

I disagree with your thoughts on the hole tolerances. MDF is known to real stable dimensionally since it is sawdust and glue. The holes shouldn't change diameters. I live in South Georgia where we see 20% humidity in the winter and 90-98% all summer long. Over a 5 year span my holes haven't changed at all. I've never had a customer complaint about the dog's fit changing. Peter's case is the first I've heard of the holes changing diameters and he admits it's been some pretty extreme conditions.

Before the MFT/3 (and before the dogs) Festool's holes varied almost every year. The holes could be 19.80 to 20.20 mm depending on which year you bought the table. Since the MFT/3 came out 5 years ago, Festool has kept the hole size consistent indicating they can keep the tolerance tight. Happy accidents like that don't just happen in manufacturing, trust me.

 

[Corwin]

...
I will tell you from my experience, and customer feedback, 1/2 of .001" can make all the difference in the world on how the dogs fit in the holes. That small amount is definitely noticeable to any one using the dogs.
...

Exactly! 

 

[rmwarren]

...
I will tell you from my experience, and customer feedback, 1/2 of .001" can make all the difference in the world on how the dogs fit in the holes. That small amount is definitely noticeable to any one using the dogs.
...

Exactly! 

Which was my primary point below, on my own MFT the same dog "drops" into one hole and "slips" into the next, all across the MFT.

The holes could be 19.80 to 20.20 mm depending on which year you bought the table. Since the MFT/3 came out 5 years ago, Festool has kept the hole size consistent indicating they can keep the tolerance tight.

Festool maintains a great tolerance, nothing like .2mm (.008") variations, but on my own MFT there are certainly .001" variations.

RMW

 

[Harvey]

With a conventional micrometer I measured  the same dogs to within 0.0006 inch.
Of course, your mileage may vary.
Regards

Edit:
What I meant to say was the variation from between the dogs was plus minus 0.0006 of an inch- the absolute size of the dogs were 0.7775 (for two) or 0.7781 (the other three) by my measurements.

 

[NuggyBuggy]

Thanks everyone for the replies - very informative.

I should have checked in here earlier to note that  I have indeed been in touch with Steve @ Qwas and I can say he is a fine gentleman and did everything he could - certainly more than he needed - to make this customer happy.  I feel dirty for having bought my first set of dogs from another company.

I also told him that I think his dogs have really changed the way I work with my MFT.  I don't think I ever use the accessories that came with my MFT anymore.  I certainly don't use that hinge thing, nor have I used the fence in a very long time.  I sigh deeply every time I have to work with a piece that's too wide to use the dogs on the MFT.

Thank you, Steve.