Festool 20mm Hinge Bit + Router Runout.

[lasttoleave]

I use Precsion dogs and they fit snugly, with no slop.

Thanks for informing me of that, it's made me happier to persevere down this route further knowing other people have got achieved using the same tools.

Can I ask what model router you are using to get these results?

Set the router on its slowest speed and plunge as fast as you can in one go. See if that makes a different sized hole and eliminates the burning.

I have tried plunging relatively fast, but there seems to be a lot of resistance and burning almost immediately which makes me ease up slightly by instinct.

I will try some more tests using each router and maybe some time material to begin with (12mm MDF)

When I make my holes in MDF, I make my plunges one continuous plunge, adjusting the speed depending on bit size.  Even when metal machining, with the rigidness associated with that type work there is ridging, probably not as pronounced, but none the less present.  In metal working precise holes are made oversize and then reamed to final size.  Try slowing the speed, adjusting plunge rate and making a continuous plunge.

Thank you, I will try and incorporate these techniques. Do you have a lot of burning with your setup or are the holes pretty much clean? Would you mind describing the pressure you have to apply when boring your MFT holes?

I think I'll have to push pretty hard to bore the hole in one continuous plunge, but its worth trying. Does everyone use their routers on the slowest speed for this task?

Thanks.

 

[rst]

I'm using a 1400 and I do not get much burning, again...practice on some scrap to refine the process.

 

[lasttoleave]

I'm using a 1400 and I do not get much burning, again...practice on some scrap to refine the process.

Great, I took my router apart and did a bit of maintanence. I cleaned up the bit so everything was fresh and took the advice everyone has offered and had some better results. I've minimised the burning and plunging faster in one continuous motion definitely made the ridges a lot less defined. Meaning the holes were cleaner and now measure between 20.1 and 20.2mm which is much better, but the dogs I'm using are still too loose to use accurately for alignment on the MFT.

I have used a dial caliper on the bit shank and can't measure any concerning runout, but it could still be the router causing some runout enlarging the hole when in use.

I have yet to borrow a Festool router to test with, but assuming for a moment that the festool router would produce holes that fit the Precision Dogs well, I am just concerned that I was planning to use a guide bush and a CNC'd template to locate the router and holes, but I am not sure this would be stable enough to bore the holes with absolutely no movement.

Would anyone reccomend trying an alternative method to create the holes exactly the right size, or is this described method mostly considered the best for MFT tops?

 

[greymann]

To really echo part of John H. statement.

I use my 20mm bit in making tops (using my 1400 though).  I found by trial and error that using a slightly smaller 1/2 " shank straight bit, actually a Whiteside 25/32 to hog out the majority gave the best results.  Since the 20mm is just doing the last bit of sizing, there is no burning and all dogs I've tried fit great.

If something like this doesn't work for you, my bet is on the router being the problem.

Dick Perry

 

[greg mann]

I think you are still experiencing runout issues. At first you had rough, oversize, burnt holes. You cleaned all the components and all of those characteristics got better. You may have reached the quality limit of your router/collet capabilities. I say this because I do not know the quality available to the Triton 8mm combo. If you get really good results with your buddy's 1010 then you know your Triton is a bit less capable than what others have been able to do with their Festool routers. My guess, for what it is worth, is the culprit is probably your collet.

If you can check runout at the cutting edges I think you will find more than .001. Also, look for the trailing edge behind the cutting edge possibly running out more than the cutting edge itself. This would cause the burning and the poor finish in the hole.

 

[overkill19]

Sorry for digging up old thread, but heres my bit that showed up today! Im gunna try filling down the wide side edges to get closer to 20mm. I was surprised the difference between the two blades.

 

[greg mann]

The measurement in your first picture looks invalid. I suppose it could be optical illusion but I don't think so. Turn your caliper blades at a right angle to the centerline of the cutter and rotate the tool through them to find the high spot on the cutting diameter and the non-cutting pads. I am sure they were ground together and should be the same diameter, probably closer than you can fully discern with calipers. If you have an indicator you could chuck up the bit in your router and pass all features by the indicator to determine how well it runs.

I would advise against trying to file the surfaces as they are carbide and pretty much untouchable to anything but a diamond hone, and you have no way to gauge your progress. If you rely on calipers they will deceive you. Better use as is and experiment with technique.

 

[Bohdan]

If those readings that you got were accurate I would send the cutter back as 0.13 mm oversize on the cutter is excessive.

I made my own dogs and they fit into MFT holes and the ones that I drilled using a festool bit exactly the same.

 

[overkill19]

The measurement in your first picture looks invalid. I suppose it could be optical illusion but I don't think so. Turn your caliper blades at a right angle to the centerline of the cutter and rotate the tool through them to find the high spot on the cutting diameter and the non-cutting pads. I am sure they were ground together and should be the same diameter, probably closer than you can fully discern with calipers. If you have an indicator you could chuck up the bit in your router and pass all features by the indicator to determine how well it runs.

I would advise against trying to file the surfaces as they are carbide and pretty much untouchable to anything but a diamond hone, and you have no way to gauge your progress. If you rely on calipers they will deceive you. Better use as is and experiment with technique.

The callipers are turned for the picture sake only! I measured that thing 10x

I actually set calliper and tried to pass bit from bottom up from several turns. They are defiantly two different measurements.
Ill pullout my dial calliper tomorrow and try and make a video.   

 

[Michael Kellough]

That bit is not made to make a 20mm hole. It's made to make a hole that a 20mm fitting fits into so it needs to be a little oversized.

 

[overkill19]

That bit is not made to make a 20mm hole. It's made to make a hole that a 20mm fitting fits into so it needs to be a little oversized.

I get what your saying but the label clearly says 20mm ?

 

[Bohdan]

I would expect that a fitting, designed to go into a 20mm hole, would be undersize so you could use a standard 20mm drill.

 

[Cheese]

I know when it comes to twist drills, because a drill bit will always produce a hole larger in diameter than the drill bit itself, twist drills are usually manufactured to be slightly undersized.

For instance, take a 1/4" drill bit, it will probably measure .2485" to .2490", yet it will produce a hole with a diameter of .250" to .251" and as it becomes dull, the hole diameter will increase further.

I just measured a nominal 20mm Zobo bit and the diameter was actually 19.94-19.95mm.

I'd expect/assume that in manufacturing a Festool router boring bit, the tolerances/specs/practices used would be similar. [2cents]

 

[overkill19]

https://vimeo.com/197711590

You be the judge!

 

[overkill19]

Not sure if it worked
http://s288.photobucket.com/user/overkill19/media/DDA0116D-91FC-435A-AB97-40B423B3B042.mp4.html

 

[overkill19]

https://vimeo.com/197711590

You be the judge!

The other blade is smaller, this one is the widest point i could find

 

[overkill19]

Tomorrow ill gunna go down to Prime Fastener, they carry CMT bits. Ill take my mic with me, if they have a 20 mm in stock

 

[greg mann]

So I did what I should have before posting anything and you are correct. The spurs are bigger than the main cutting edges. Looking closely they are designed to essentially score the hole ahead of the main cutters. Mine measured about .0005 smaller than yours but it is well used at this point. The tool is certainly designed to cut a hole that allows 20mm hinge cups to slip in without effort. This makes it a sub-optimal tool for dog holes as is. There is a lot of backtaper in both the spurs and the main cutters so it could be altered with a diamond file but I would look for a different tool or approach. That said, I don't believe loose holes will impact accuracy much if you use dogs that have heads to keep them from falling through and then reference off the heads. Once the dogs are pushed against the wall of the hole it will be just as accurate as a tight fit.

 

[overkill19]

So I did what I should have before posting anything and you are correct. The spurs are bigger than the main cutting edges. Looking closely they are designed to essentially score the hole ahead of the main cutters. Mine measured about .0005 smaller than yours but it is well used at this point. The tool is certainly designed to cut a hole that allows 20mm hinge cups to slip in without effort. This makes it a sub-optimal tool for dog holes as is. There is a lot of backtaper in both the spurs and the main cutters so it could be altered with a diamond file but I would look for a different tool or approach. That said, I don't believe loose holes will impact accuracy much if you use dogs that have heads to keep them from falling through and then reference off the heads. Once the dogs are pushed against the wall of the hole it will be just as accurate as a tight fit.

I agree totally but the label clearly says 20mm not sloppy 20mm!

I was going to make my own dogs but this was based on 20mm hole. So i guess ill get them coated to make up the slop.

 

[greg mann]

So I did what I should have before posting anything and you are correct. The spurs are bigger than the main cutting edges. Looking closely they are designed to essentially score the hole ahead of the main cutters. Mine measured about .0005 smaller than yours but it is well used at this point. The tool is certainly designed to cut a hole that allows 20mm hinge cups to slip in without effort. This makes it a sub-optimal tool for dog holes as is. There is a lot of backtaper in both the spurs and the main cutters so it could be altered with a diamond file but I would look for a different tool or approach. That said, I don't believe loose holes will impact accuracy much if you use dogs that have heads to keep them from falling through and then reference off the heads. Once the dogs are pushed against the wall of the hole it will be just as accurate as a tight fit.

I agree totally but the label clearly says 20mm not sloppy 20mm!

I was going to make my own dogs but this was based on 20mm hole. So i guess ill get them coated to make up the slop.

I think the issue here is recognizing the job for which the tool is designed. If it were made to exactly 20mm we would probably be reading posts about dissatisfied users pounding hinges into undersized holes, and not being able to remove them if that were necessary. Maybe there would even be complaints about splitting. 20mm is the nominal size and the tool is marked appropriately for its intended purpose, which is 20mm hinges. I understand the desire to use the tool for your dogs but that is not what it was designed for.