Custom size MFT table

C

Claimdude

Member
Joined
Feb 20, 2011
Messages
461
Hi All,

I am planning the construction of a new work bench (non-mobile). I want to use a MFT style perforated top rather than the typical laminated top. My questions are as follows:

1. What size should I make the holes?
2. Is there a small drilling template that can be used to drill the holes in proper alignment etc?
3. What thickness MDF (or what other material would you use)?
4. What side rails should I use (don't want top use the Festool MFT sides due to custom size of table top) would you recommend? No need to be compatable with the hardware on the MFT as I will use the custom bench dogs that are advertised here and on ebay. The rails would add some sort of side clamping ability similar to using a Kreg clamp.

Thanks in advance for your suggestions!

Jack
 
20mm is a good size (and the same as the Festool MFT) as it allows you to drop a clamp through without too much bother. Go too thick on the top and you will limit flexibility.

Are you going to make the top replaceable? (Sacrificial for cutting, etc?) - design consideration there!

I'd seriously hunt for someone with a cnc or like to cut your holes - you can do it fairly accurately with the right gear ... but one little mistake and ...

I don't think you can go too wrong with Incra and Kreg rails.

Kev
 
I've kinda flip flopped back and forth regarding 20mm or3/4" holes. 3/4" router plunge bits or forstners are more readily available in NA. Until recently Lee Valley's range of bench dogs and clamps only accommodated 3/4" holes as well. Now that the Grandpa Valley is offering their goods specific to 20mm holes that opens up possibilities. 20mm gives you that extra little bit of clearance as well for dropping in Festool style F clamps, which you're gonna want. So contrary to previous advice given I'm gonna recommend 20mm dog holes for maximum flexibility. As far as a template or jig for drilling the holes accurately take a look at home made LR32 systems posted somewhere on this forum, if access to affordable cnc isn't an option. On my prototype cart/bench, which i'm still using  I just laid out a grid and drilled with my T-15 and a forstner. super accuracy with the grid spacing wasn't as important to me at the time and really isn't now but for a permanent bench you would probably want an accurate spacing as you can use the grid in combination with some dogs for accurate  angles .

Just my two bits
Keep us posted on your progress
 
Kev said:
20mm is a good size (and the same as the Festool MFT) as it allows you to drop a clamp through without too much bother. Go too thick on the top and you will limit flexibility.

Are you going to make the top replaceable? (Sacrificial for cutting, etc?) - design consideration there!

I'd seriously hunt for someone with a cnc or like to cut your holes - you can do it fairly accurately with the right gear ... but one little mistake and ...

I don't think you can go too wrong with Incra and Kreg rails.

Kev
Click to expand...

Yes, it will be replaceable.
On the CNC if I found one locally what do you think it would cost me to have it done? I have never had any custom CNC work done so have no frame of reference.

Thanks for your help

Jack
 
GhostFist said:
I've kinda flip flopped back and forth regarding 20mm or3/4" holes. 3/4" router plunge bits or forstners are more readily available in NA. Until recently Lee Valley's range of bench dogs and clamps only accommodated 3/4" holes as well. Now that the Grandpa Valley is offering their goods specific to 20mm holes that opens up possibilities. 20mm gives you that extra little bit of clearance as well for dropping in Festool style F clamps, which you're gonna want. So contrary to previous advice given I'm gonna recommend 20mm dog holes for maximum flexibility. As far as a template or jig for drilling the holes accurately take a look at home made LR32 systems posted somewhere on this forum, if access to affordable cnc isn't an option. On my prototype cart/bench, which i'm still using  I just laid out a grid and drilled with my T-15 and a forstner. super accuracy with the grid spacing wasn't as important to me at the time and really isn't now but for a permanent bench you would probably want an accurate spacing as you can use the grid in combination with some dogs for accurate  angles .

Just my two bits
Keep us posted on your progress
Click to expand...

20mm it is then. Accuracy will be critical because I plan on using the dog holes with the rail dogs and so forth. The top will be replaceable. Is 3/4 MDF suitable as far as thickness?

Jack
 
in response to your points:
1) I'd go with 20mm holes so that you can use Qwas dogs
2) Know anyone with an MFT? If you do that's probably one of the easier ways- just borrow the top, and just copy the pattern with a flush trim router bit (I'd use a 1/2" drill bit and drill to hog out the waste first, then use the 1/2" flush trim bit to copy exactly). If you need to shift it down, just move down however many rows you need, and pop in a few Qwas dogs so that you keep the squareness.

3) How big is the top going to be? 3/4" or 19mm MDF is sufficient, if it needs to be larger, just brace it from the bottom

4) I'd go with a high quality flush mounted T-track for this option, if you're just using it for clamping. Just rout out a 3/4" x 1/2" deep groove, and fit some Incra T-track in (you can get these in a wide variety of lengths. Incra t-tracks fit the festool clamps perfectly. On top of that it'd be huge for any jigs you want to attach with t-tracks, knobs, etc.

Claimdude said:
Hi All,

I am planning the construction of a new work bench (non-mobile). I want to use a MFT style perforated top rather than the typical laminated top. My questions are as follows:

1. What size should I make the holes?
2. Is there a small drilling template that can be used to drill the holes in proper alignment etc?
3. What thickness MDF (or what other material would you use)?
4. What side rails should I use (don't want top use the Festool MFT sides due to custom size of table top) would you recommend? No need to be compatable with the hardware on the MFT as I will use the custom bench dogs that are advertised here and on ebay. The rails would add some sort of side clamping ability similar to using a Kreg clamp.

Thanks in advance for your suggestions!

Jack
Click to expand...
 
Thanks guys! As it turns out my brother has been doing machine work for a lot of years. I asked him if he knew anyone in town with a CNC that could cut the holes and he does! Anyone have a technical drawing that gives exact dimensions for the hole pattern, ie distant apart from center to center and so forth?

Thanks again,
  Jack
 
Claimdude said:
Kev said:
20mm is a good size (and the same as the Festool MFT) as it allows you to drop a clamp through without too much bother. Go too thick on the top and you will limit flexibility.

Are you going to make the top replaceable? (Sacrificial for cutting, etc?) - design consideration there!

I'd seriously hunt for someone with a cnc or like to cut your holes - you can do it fairly accurately with the right gear ... but one little mistake and ...

I don't think you can go too wrong with Incra and Kreg rails.

Kev
Click to expand...

Yes, it will be replaceable.
On the CNC if I found one locally what do you think it would cost me to have it done? I have never had any custom CNC work done so have no frame of reference.

Thanks for your help

Jack
Click to expand...

Unfortunately I'm on the wrong part of the planet to give you any guidance on this ... The cost of CNC work can be highly variable depending on the typical work performed ... you'd need some local guidance, but trying someone "out of the phone book" is likely to come back expensive on first enquiry.
 
3/4" is about the max you want. Anything thicker won't allow the Festool j clamps to be used.
 
Qwas said:
Drawings are available at Seneca Woodworking blog.

MFT Top CAD Drawings
Click to expand...

Qwas,

I really appreciate the link for the cad drawing and pdf. I noticed on the pdf that Seneca had the holes at 20.2mm rather than 20mm for the hole diameter. Everything I have says the holes need to be 20mm. My brother whis a machinest was getting a couple of bids to have the MDF holes cur called today to tell me that the cnc process on the MDF if set at 20mm would create a slightly small hole after machining due to shrinkage in the material. I told him that I need a 20mm hole when complete and he said the cnc would need to be set for a slightly larger hole to accomplish that.

Is that why the Seneca PDF shows a 20.2 mm hole? I want to be real sure before I have the guy pull the trigger. I'd be real unhappy if my yet to be Qwas dogs and others didn't fit.

Thanks again,

Jack
 
I haven't heard of the holes coming out smaller than the diameter they were cut to. Typically holes will end up slightly larger than the drill size. I am not a CNC machinist so I couldn't say why he thinks the holes will be smaller. However, that shouldn't be your concern. You need to specify a finished hole size and it's up to them to decide how to get to that size.

Ideally you want a finished hole size of 20.07 to 20.11 mm. These will allow a 20 mm peg (and all Festool accessories) to slide into the hole. 20.2 mm is rather large and I think he got those numbers from the last run of the MFT-1080. The last years those were made they had holes of 20.17 mm. I have one of them tables and the holes are definitely larger than need be.

While I can find no proof that loose fitting dogs are more accurate, I do believe tight fitting dogs accomplish nothing but grief for the user. Allow some slack for the dogs to slip in and out and using them will be more enjoyable. When the dogs are used properly, some slack will not affect accuracy at all.

Worse case, if the Qwas Dogs fit too tight, contact me and I will correct the problem.  [smile]
 
Just finished a 51"x 39"x3/4" MDF top (because that was the size of the sheet I had), drilled evenly spaced 3/4" holes on 96mm centers (columns and rows) across the entire top, using the lr32 and a 3/4" upspiral Osrud bit from Lee Valley.  It checks out as square and as accurate as I'll ever need.  Festool clamps work fine; need 3/4" dogs - using Kreg.  Whole process took less than 20 minutes.

DrD
 
I found a custom cabinet shop in NW Louisiana with 3 CNCs and they have milled me a top out of 3/4 MDF, 71.90" x 41.575 with 20mm holes - 96mm on center. If anyone within driving distance of Shreveport, LA wants to get one made PM me and I will give you the contact info.

Jack
 
Claimdude said:
Qwas said:
Drawings are available at Seneca Woodworking blog.

MFT Top CAD Drawings
Click to expand...

Qwas,

I really appreciate the link for the cad drawing and pdf. I noticed on the pdf that Seneca had the holes at 20.2mm rather than 20mm for the hole diameter. Everything I have says the holes need to be 20mm. My brother whis a machinest was getting a couple of bids to have the MDF holes cur called today to tell me that the cnc process on the MDF if set at 20mm would create a slightly small hole after machining due to shrinkage in the material. I told him that I need a 20mm hole when complete and he said the cnc would need to be set for a slightly larger hole to accomplish that.

Is that why the Seneca PDF shows a 20.2 mm hole? I want to be real sure before I have the guy pull the trigger. I'd be real unhappy if my yet to be Qwas dogs and others didn't fit.

Thanks again,

Jack
Click to expand...

I would follow Steve's guidance on the actual MFT hole diameter(s).  He has done extensive research for his products and in the end making your holes nicely accommodate the Qwas dogs is what is important.  Use the Seneca PDF drawing to generate the CNC toolpaths for the hole positions and not particularly for hole size -- the ~20.2 mm that I measured just happened to be what one of my tables measured at that  point in time.
 
RonWen said:
Claimdude said:
Qwas said:
Drawings are available at Seneca Woodworking blog.

MFT Top CAD Drawings
Click to expand...

Qwas,

I really appreciate the link for the cad drawing and pdf. I noticed on the pdf that Seneca had the holes at 20.2mm rather than 20mm for the hole diameter. Everything I have says the holes need to be 20mm. My brother whis a machinest was getting a couple of bids to have the MDF holes cur called today to tell me that the cnc process on the MDF if set at 20mm would create a slightly small hole after machining due to shrinkage in the material. I told him that I need a 20mm hole when complete and he said the cnc would need to be set for a slightly larger hole to accomplish that.

Is that why the Seneca PDF shows a 20.2 mm hole? I want to be real sure before I have the guy pull the trigger. I'd be real unhappy if my yet to be Qwas dogs and others didn't fit.

Thanks again,

Jack
Click to expand...

I would follow Steve's guidance on the actual MFT hole diameter(s).  He has done extensive research for his products and in the end making your holes nicely accommodate the Qwas dogs is what is important.  Use the Seneca PDF drawing to generate the CNC toolpaths for the hole positions and not particularly for hole size -- the ~20.2 mm that I measured just happened to be what one of my tables measured at that  point in time.
Click to expand...

Thanks Ron for chiming in. I did follow Steve's advice and gave the CNC guy the finished hole diameter to I needed per Steve's suggestions. The panel is complete and I will be picking it up this week. I'll let y'all know how it turns out. Won't be able to test it with actual dogs though until I receive my Qwas combo kit from Bob Marino.

Jack
 
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