# MFT top with the RS CNC jig



## Steve Maskery (22 Mar 2017)

After DiscoStu's excellent review of the Parf MFT system and PAC's subsequent recommendation of the RS CNC's jig, I bought the latter. I did not realise at the time that he also sells the dogs, otherwise I would have bought them, too, but by the time I found that out I'd already bought the Veritas Parf dogs from Axminster. Pricey at nearly £26 – more if you have to pay for delivery – but they are superbly made and come in a plastic tube for storage. Very excellent. They are also stainless steel rather than aluminium, and taller than the RS ones, so we are not completely comparing like with like.

The RS jig arrived in a cardboard box. Well not really a box, to be honest, more an assemblage of pieces of cardboard taped together. Once I'd opened it all up I no longer had a box in which to keep it! I'm trying to make a box out of the bits, but I'm finding that Duck tape doesn't stick to cardboard very well. I'll have to find my parcel tape gun.

The jig itself looks superb. It has, engraved on it, a reminder of the cutter required – 12.7mm with a 30mm bush – two plastic drill bushes and two plastic locating pegs for incrementally repositioning the jig.

The first task is to find out what size holes my router produces in reality. So on a piece of scrap I made a test hole. 







It was not very clean in the wood and the dog did not go in at all. So I tried a different 1/2” cutter and used a piece of MDF instead of the wood and that was sloppy. The jig comes with a piece of aluminium tape, which you can use to wrap around your bush to increase the diameter slightly, and after a few test holes I got it good.






The jig has two long edges labelled A and B. We start with edge A. My workpiece is a sheet of MDF and, starting from the short edge, I clamped the jig leaving a few millimetres to be trimmed off. 






The first row of holes is routed out. 






I don't think I shall need them, but the jig also provides drill bushes for drilling fixing holes.






Then the jig is removed, turned through 180 degrees and the pegs used to set the jig in the right place to continue.






But. I had a problem. The pegs didn't fit, they were too tight. Furthermore, they would fit in some of the holes but not the ones necessary for the repositioning pegs. So I had to use a bit of sandpaper to ease them out. Feeling a bit miffed, I carried on but the dogs fitted some holes better than others. And then the penny dropped.

I do have dust extraction on my router, but the thickness of the jig means that the actual cutting is further away from the port than would normally be the case. I was getting some debris around the outside of the hole making the hole too small. Vacuuming out that debris and re-cutting solved the problem. So I strongly recommend that you test every single hole for fit before you reposition the template, especially on that first row, as you'll never get it back in the identical place once you've taken off the clamps.

And so I continued, two rows of holes, check for fit, reposition jig and repeat. 






I created 15 rows of 11 holes, using about 2/3 of the sheet. That means that I can crosscut a whole 8x4 sheet if I want to. I'll probably use the remaining 1/3 to make a smaller one.






This took me a couple of hours. It was taking about 15 minutes between repositioning the jig, once I'd got into the swing of it.

Verdict – it's a very good piece of kit at an affordable price. I have got on very nicely for many years setting up my track with either a roofing square or my Square of Thales, but I have to admit that this beats them both hands down. 






If I were to be picky I'd say that I wish the packaging was more user-friendly and if the pegs had a chamfer on them it would be easier to locate the holes, but really that is all there is to moan about. I've just got to find somewhere safe to keep it.

I'm glad I bought it.


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## transatlantic (22 Mar 2017)

So are you planning on making several of these?

I picked up the whole top pre-milled for only £5 more including postage, I figure its going to last at least a few years if not more if you look after it. But I guess the jig makes senseif you want to mak custom sizes. I kind of wish I'd seen the birch plywood verison from that website though, would have definately gone for that over MDF.

I just need to find some cheap clamps for mine now.


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## Steve Maskery (22 Mar 2017)

That's a fair point, T. TBH I didn't do a lot of research. I just saw it and thought it looked good. I've been thinking if getting an MFT for quite a long time, but this was pretty much an impulse buy.


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## siggy_7 (22 Mar 2017)

I have this jig; I encountered difficulty with the guide bush method of getting a perfectly sized hole as well. The jig itself is very nicely made, but I think using a guide bush to get the exact hole size is a bit of a PITA. I'm planning to make a guide bush for my router sized to exactly match the jig, then I can use a 20mm router bit with the router just centered in each hole by the bush to speed the job up and improve repeatability.

For storage of the jig I just hang mine from a couple of nails in a rafter.


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## sammy.se (25 Jul 2020)

I tried using this jig today. The holes were too sloppy :-(

I tried two different routers with two different bushes and several 12.7mm cutters. Trend and Eli branded, so they are good. 

All sloppy.

So the tools are fine, the jig template is too wide for the dog hole. 

I tried masking tape around the bush and it worked better. A better fit, but I need two layers of tape. 

I'm wondering if I should go out and buy some foil tape, because presumably the foil tape will not compress, while the masking tape will? 

What do people think?

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## Nelsun (25 Jul 2020)

Foil tape is what I've seen jig manufacturers recommend and even supply with their jigs. Not sure how well the tape will hold up...

It's a bit of a rabbit hole to go down once you start seeking the perfect fit between dog and hole.


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## sammy.se (25 Jul 2020)

Thanks Nelson.

I think I'll give foil tape a go, for the sake of £5 or so...


Thanks for the heads up on the rabbit's hole. 

This will be my first MFT, and I'm hoping to get it snug enough for accurate cuts and assembly for sheets. I have 6 dogs which came with the jig (20mm diameter exactly) so I'm hoping to at least get those fitting nicely. I'll worry about other dogs as/when I need them.



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## porker (25 Jul 2020)

sammy.se":kft658mj said:


> I tried using this jig today. The holes were too sloppy :-(
> 
> I tried two different routers with two different bushes and several 12.7mm cutters. Trend and Eli branded, so they are good.
> 
> ...



I bought the dogs and the jig together and the fit was great with one thickness of the aluminium tape supplied around the guide bush. I think parf dogs and some others are a slightly different diameter (undersized) compared with the dogs from the jig manufacturer. 
I have made two tops in a Paulk type design, the first was not 100% perpendicular but this was due to a lack of concentricity with a very old and worn Erbauer router. I re-did it with a Hitachi router and it was spot on.


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## sammy.se (25 Jul 2020)

Sounds like tape is what I need. I bought the jig used (in great condition) so I probably just need the tape.

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## sammy.se (25 Jul 2020)

Two layers of foil tape has worked a treat - thanks all

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## Nelsun (25 Jul 2020)

One tip I have is to watch for gunk build-up on the bit as this can lead to ever-so-slight variances in hole size. DAMHIKT!


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## sammy.se (25 Jul 2020)

porker":1dn9799o said:


> sammy.se":1dn9799o said:
> 
> 
> > I tried using this jig today. The holes were too sloppy :-(
> ...



Can you tell me more about the concentricity - do you mean your holes were oval? 

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## sammy.se (25 Jul 2020)

Nelsun":3qutjs3a said:


> One tip I have is to watch for gunk build-up on the bit as this can lead to ever-so-slight variances in hole size. DAMHIKT!


Thanks! Will look out for that.

Should I be expecting 90 degrees exactly from the worktop, or is there a tolerance, e.g. +/- 0.2 degrees? 

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## Nelsun (25 Jul 2020)

sammy.se":1v8sd1b8 said:


> Should I be expecting 90 degrees exactly from the worktop, or is there a tolerance, e.g. +/- 0.2 degrees



That'll come down to the accuracy of the router plunge but I would expect it to be 90 (or as close as you can't tell).


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## sammy.se (25 Jul 2020)

Thanks. I'm going to try with two different routers and see what comes out better. 

Both routers (Trend 1/4" and Elu 1/2") have bushes that fit snuggly, so there's no play there, but perhaps there might be defects in other aspects...

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## porker (25 Jul 2020)

sammy.se":23ru9mxl said:


> porker":23ru9mxl said:
> 
> 
> > sammy.se":23ru9mxl said:
> ...



The issue with the concentricity was with the cutter to the guide bush. In theory if you used the router in the same orientation every time you moved the jig to a new position you would be OK but I didn't and it meant that the holes were offset between repositioning of the jig. Not by much but not as accurate as I wanted. Mine is about 4' on the longest edge and if I lay a straight edge along it with a few dogs in, I can't see any inaccuracy so good enough for me.

I actually turned an aluminium guide on the lathe with a 1/2" hole in the middle and the outside to fit inside the guide bush as there was some adjustment on where the guidebush would locate. The bearings finally gave out on the Erbauer (it was very old, I think their first iteration) so I bought a Hitachi which was spot on. It's the only real way the holes can be out as far as I can tell because as said earlier the jig is very accurately manufactured.


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## Doug71 (25 Jul 2020)

Steve, I see you are using a Festool OF1400 router. Great router but it does have a reputation for the snap in bushings/copy rings not being concentric to the cutter and it's not adjustable, mine is ever so slightly out, maybe that could have been part of your problem.


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## Steve Maskery (25 Jul 2020)

Possibly, I've not checked. That was possibly the one and only time I've used a guide bush with it.
I used to have a few Elus. An original MOF96 which had conked out, a 96e which was wonderful, and a 177e which was the absolute bees knees. Centricity was never a problem at all, bang on, first time every time. I wish I still had them


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## Sideways (25 Jul 2020)

I have RS CNC dogs, one of their ready cut tops and the parf guide. The dogs fit both ready and home made tops great. I have also bought veritas parf dogs in the past and had to return them as the fit was unacceptably sloppy at about 0.2mm clearance if I remember.
Not all dogs are equal....


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## sammy.se (26 Jul 2020)

Phew, what a faff. Finally got my MFT type holes completed

So, a job I thought would be a couple of hours took the best part of two days... 

So, in summary: I did have a concentricity issue, on both of my routers. I tested both and found the compound variance across the width of the table, which meant the holes weren't perpendicular.

A lot of trial and error, and carefully placed tape (foil and masking) later, I have some accurate holes! This is according to a quick test I done just before packing up.

In all honesty, if I find errors and some holes out of square, I shan't bother with the jig anymore and just buy a ready made one. It's just not worth all the fettling I had to do.

I'll post some more details later in case this helps someone in future.









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## Hornbeam (26 Jul 2020)

This might be a real ignorance on my part but I am struggling to see what an MFT does or how it is used
I have a bench with a row of dog holes, an end and front vice and that holds everything
Ian


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## sammy.se (26 Jul 2020)

Hornbeam":1kh4kspm said:


> This might be a real ignorance on my part but I am struggling to see what an MFT does or how it is used
> I have a bench with a row of dog holes, an end and front vice and that holds everything
> Ian


Because the grid of holes are perfectly square, it allows you to align boards and track saws at perfect right angles, allowing accurate cross cutting, as one example.

Your bench can do everything else an MFT can, hold downs, etc.

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## Hornbeam (27 Jul 2020)

sammy.se":qb94zou1 said:


> Because the grid of holes are perfectly square


And I thought you were trying to make perfectly round concentric circles. (hammer) 

I think I would need to see it in use to really get it
Thanks
Ian


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## sammy.se (27 Jul 2020)

Here is a good overview of what an MFT type table can do:

https://youtu.be/AMnAyBrFHCE

(This video is very 'Parf' branded, but the concept is the same for all of these holey tables)


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## Steve Maskery (27 Jul 2020)

This is how I use mine
https://www.youtube.com/watch?v=TkaQVencYoI
S


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## Hornbeam (27 Jul 2020)

Thanks Sammy and Steve for the links and explanations and you tube links.
Im not really getting it but then I would use the panel saw rather than a track saw
Thanks again Ian


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