Using the MFT top as a router template?

[lasttoleave]

Hello,

After struggling with my Veritas parf dogs I invested in some Precision rail dogs/bench dogs and they fit much better, so the accuracy of my MFT has increased dramatically when using the bench dog method.

I need to make a replacement MFT top, and I decided it would be best to use my existing one as a router template, but after routing a few holes with a 2" long bearing guided cutter the new holes aretighter than the originals, and I'm certain that once they have eased in and compressd slightly, they will probably be less accurate than the existing top in terms of the grid alignment. I know we are talking fractions here, but I don't want to waste time/effort on something that won't be as good.

Can anyone think of a reason why this might be the case? I've used a few different flush trim bits but all result in the same thing.

I stuck the new top to the original with plenty of double sided tape, so I don't think it's got anything to do with the alignment between the two pieces of MDF.

Any suggestions before I hold out and buy a new top from Festool? (I've looked for local CNC places but nobody seems to bother if you only want one or two)

Thanks

 

[Wuffles]

Where are you in the UK?

 

[promark747]

My guess is that the router bits are a few to several thousandths smaller than the bearing.  I don't know what the standard difference is (not counting wear), but I assume they are designed not to be exact-- so that you don't dig into the template.

 

[socaljohn]

How do the Parf dogs fit in the new holes?

 

[hitandruntz]

Could be dust build up on the bearing when your routing. Or your bit is slightly smaller than the bearing. I used my mft as a template and I had  the same thing happen. I went back and rerouted the problem holes again and that took care of the problem.

 

[lasttoleave]

How do the Parf dogs fit in the new holes?

They're still actually quite slack in the routed holes, so they aren't much use for aligning the guide rail etc. The standard MFT fence and rail adjustment is much more accurate than using the Parf Dogs. The rail dogs/bench dogs from Precision Dogs are much better.

Could be dust build up on the bearing when your routing. Or your bit is slightly smaller than the bearing. I used my mft as a template and I had  the same thing happen. I went back and rerouted the problem holes again and that took care of the problem.

The strange thing is, after going back over the same holes and firmly pressing the router sgainst the inside wall of the template hole, it did make the finished hole a better fit for the bench dogs, but after routing 5 or 6 of them this way I placed a bench dog in 3 of the holes then laid a straight edge along them and found a rock on the middle bench dog, meaning I had lost some of the accuracy of the CNC'd top. I also found that doing this loosened the hole in the template/original top which means the router may have skimmed some of the original hole too.

I am going to look for CNC/Laser cutting places that will make me a 20mm template and a 30mm template I can hopefully use with a guide bush after reading a few peoples experiences and reccomendations, that seems the way to go!

I might try and borrow a different flush cut bit too and see if that does the trick.

Thanks for the advice.

 

[Holmz]

...
I need to make a replacement MFT top, and I decided it would be best to use my existing one as a router template...
...

How about a forstner bit and a way to keep the drill 'a plumb'?

 

[DB10]

Something like this maybe?
I already had The off cut of MDF, drill stand was $10, using a sys mft top as a template and the 20mm forstner bit I already had. If this works out ok it will be a cheap MFT top to use on site.
I might add that this attempt Is not in anyway aiming for the precision that most would expect from an MFT in a shop, but as a cutting clamping board for site use where it will get beaten up.
[attachimg=1]

 

[Bohdan]

[member=42735]DB10[/member] are you measuring or using dogs to index the rows?

 

[promark747]

DB10,

Does the MDF come out of the top of the SYS-MFT pretty easily?  Never thought of using it as an index for drilling holes, but that looks like an excuse to get one.

 

[Holmz]

Something like this maybe?
...

I like it DB10 - Where did you get the $10 stand, and who makes it?
That was exactly what I was thinking in 1220-2440.
And then slap it on top of http://centipedetool.com/ .

 

[Red Devil]

There is a great video on you tube about making Mft tops with the lr32 system.
I used a variation of the the technique to make a 5'x10' table top for my assembly bench.
At some point I'm going to try and post a video of my variation to as I did film it as best I could.

Nigel

 

[DB10]

I'm using a roofing square & dogs, not persision dogs.
Drill stand came from Bunnings
Sys Mft top comes off with six screws. Works well as a template.
Centipede stand looks interesting, thanks for posting that.

This is an exercise in cheap just using what I have lying around.
My Festool budget is blown for the time being.
I was originally going to use my OF1400, but the kit down here does not come with a 8mm collet, just a half & quarter, so to use the Festool router bit would mean another $100 for a 8mm collet and $80 bucks for the router bit, those two items adds up to the cost of a new MFT top.
If I had the LR32 System I would like to have a go at making a 4 x 8 top for the shop like many already have, but this method I'm using is ok for MFT size top, any larger and the boredom would have kicked in, glad the last of the holes are now in place.

 

[Stone Message]

In order to get the best accuracy with Parf Dogs you do need to secure them from underneath and that is the key reason that they have the 8 mm threaded hole. This also offsets the effect of holes being slightly bigger on some MFT3s.

When using a router with a bearing guided cutter and an MFT3 top as a template you cannot expect to get a true copy. With hand-held routing you are having to exert force to keep the bearing against the pattern and, if you look at it in cross section, you are applying a turning force which may take the router slightly off square.

I have been a member of the FOG for a while now and the subject of creating custom bench tops comes up time and time again. There have been some brilliant solutions, some elegant designs and quite a few that rely on a CNC machine for the hole cutting.

I have been investigating this for the last 2 years in order to come up with what I believe will be an easy and very accurate way of creating a pattern on holes on your own bench top which does not need a CNC machine. I will be making a video about this within 3 months and share my process with you. If you need any indication of how accurately I can cut things using Parf Dogs and my own custom bench tops then look at some of my recent videos.

Peter

 

[lasttoleave]

I'm sorry the subject has been brought up again, I was initially specifically asking regarding the flush trim bits and the difference in hole size but obviously I am grateful for the other input that has been added. I think I will take the advice of a few members and get a template machined up with holes to fit a 30mm guide bush then use a Festool 20mm bit that I can plunge to locate each hole. This will most likely result in a more accurate top than the flush trim bit.

I am sure that the Parf dogs are capable of great accuracy, I just prefer mine to be a closer fit to begin with and I also like the rail dog method of locating the rail as this is sometimes much quicker.

Look forward to seeing the video!  [smile]

 

[Bohdan]

[member=44952]lasttoleave[/member]

What size exactly do the 20mm Festool router bits actually drill and/or which dogs do they fit best?

 

[lasttoleave]

[member=44952]lasttoleave[/member]

What size exactly do the 20mm Festool router bits actually drill and/or which dogs do they fit best?

no idea...yet

I've heard the 20mm standard cutter and the 20mm hinge broing bit both have good results with the Qwas and Precision bench dogs. I have yet to sort out how I'm going to go ahead with mine.

 

[Stone Message]

[member=44952]lasttoleave[/member]

What size exactly do the 20mm Festool router bits actually drill and/or which dogs do they fit best?

One of the best ways to try a DIY effort is to use a 20 mm Zobo cutter. The Parf Dogs fit perfectly in the holes made by the Zobo.

Peter

 

[carlb40]

Or as you are in the uk. You could try buying a ready made one from one of the members on here, or a few that offer them over on UKworkshop.
[smile]

 

[Acrobat]

I understand its too late now as you've already drilled your holes and this will not solve the fit issue you have, but I have seen a video that showed the holey rail being used to drill consecutive holes as the router/drill was slid along (to every 3rd hole I think) to replicate the spacing on a mft dead on. A very easy and ingenious solution if you have the holey rail and lr32 plate attachment. I'm sure the video was on You tube a little while ago, so may help others if they are considering making their own tops.