Long screws - which drill?

[Neathawk Designs]

Hello,

I'm in the middle of a project replacing a large roof on a barn.  The architect has specified 8" long screws to attach the plywood.  I am putting the screws through 5/8" roof sheathing, then through 4" of foam, then 3/4" roof deck, and then almost 3" into the rafters.  My Makita 18v impact drivers are barely getting the screws in and it's going terribly slow.  In many cases the impact driver stops before getting the screw in all the way.

Which Festool drill might you recommend me trying?  I have have at least another 1000 maybe 2000 more screws to put in.  Can anyone make any comment on the comparison in driving power between a festool drill (I was looking at the PDC 18) versus a makita 18v brushless? 

On a side note - I think that part of the problem is the screws the architect specified are not really a great wood screw.  A different screw would probably make a big difference - but finding new screws and getting them approved for the project is quite a pain too -and it may not solve the issue.

Thanks!
Ryan

 

[Locks14]

For this task I'd stay away from Festool and go with Milwaukee. Either their 18v M18 Fuel 2 drill with 135nm of torque or their impact driver from the same Fuel 2 line with 203nm of torque.

 

[Drich]

I agree with Locks. I would get a impact with a 3/8 inch drive in Milwaukee and put a socket on it. Much more power that way. 167 ft pounds of torque. compared to 100 of a 1/4 inch drive. You could step up to a 1/2 inch drive is what I have used on lags bolts on decks. Tons of power then

 

[Bohdan]

Too much torque may snap the screws, because you are screwing into old and very dry timber you may need to predrill the holes. Have you tried lubricating the screws with (paraffin) wax or soap? Usually makes a big difference with old timber.

 

[WarnerConstCo.]

PDC. 

That long of screw will give any cordless impact problems, lots of shaft to twist.

I can't sink 9" timber locks with my brushless makita impact or a M18 fuel impact.

My old C12 will even finish off where those two stop.

I like the PDC quadrive plus it has a side handle.

 

[flair woodworks]

What type of drive head do the screws have?  Although I was an early adopter of the impact driver, I've since gone away from them.  The one advantage of an impact driver I see is that it constantly resets the driver in the head, making it less likely to strip the head.

Are you driving screws down?  If so, I'd probably suggest the PDC.  If you have to hold the drill up in the air and fight gravity, maybe look at the T18 and put in an 18V 2.6 Ah battery for weight savings.

 

[Neathawk Designs]

Thanks for the feedback!

I like the wax idea - I have not tried it yet.

The screws are Philips head (large philips head).  I'm actually surprised that we have yet to strip a single screw head.  Because of that, I'm not sure if the larger Milwaukees that you are referring to would work?  I've always been impressed with milwaukee's fuel line.

I was leaning toward the PDC.  Is it compatible with the 5.2 amp battery?  I have 3 of those.  I can't remember the last time I used a drill to drive a screw in.  The top section of the barn is an 8/12 pitch - so we are screwing down and it's not too bad.  The sides of the roof are very steep, and might be a little more difficult.  Is there a difference in power between the 2?  My Makita's are only 3.0 Amp batteries - I imagine the jump to the 5.2 Festool would be a substantial difference.

This is the screw that I'm using: http://www.trufast.com/products/steel_wood/14_hd.html

 

[Birdhunter]

Is predrilling a potential solution?

 

[rst]

I've run hundreds of 5 and 8" GRK structural screws with my 18v Milwaukee impact with no issues and reasonable battery life.

 

[GregBradley]

A brand name doesn't tell us anything. There is no comparison between the early Makita 18v impacts like a BTD140/141 and the later Brushless impacts. LOTS more power.  My three speed Brushless Makita has about the same power on medium as the early ones have. Bosch and Milwaukee also make more powerful impacts. You need to be specific about WHICH impact, not brand names.

The impact wrenches are setup for sockets but have no more power than the impact drivers unless they are the big body drivers, which have 7/16" hex for lineman use or 1/2" square for impact socket use. Those are more powerful, in general.

Any drill/driver will also drive this with a low enough gear. It will try to cam out of Philips drive heads more than impact drivers so you will need to press down hard and resist the torque effect, which will mean a second handle. Sounds exhausting to me.

 

[Neathawk Designs]

Hmm... not sure which models I have - But now that I think about it, they're all fairly old (the newest is the brushless and it's probably 4 years old - The oldest is probably 6 or 7 years old!).  The batteries are newer. 

Pre-drilling is an option - but it seems like it would take forever.  I picked up Drill bits for the job but haven't tried it yet. 

I really like the GRK Screws - I wish the architect specified them because I would have charged accordingly and we would be cruising through this... but at this point, I imagine switching from our current screws to a GRK version would cost another $2000 or so due to the price difference and the amount we need.

 

[Kev]

Drill/driver aside, is this a common US roofing approach? I would have thought the foam would compress over time and create knock on issues.

 

[flair woodworks]

The screws are Philips head (large philips head).  I'm actually surprised that we have yet to strip a single screw head.  Because of that, I'm not sure if the larger Milwaukees that you are referring to would work?  I've always been impressed with milwaukee's fuel line.

I was leaning toward the PDC.  Is it compatible with the 5.2 amp battery?  I have 3 of those.  I can't remember the last time I used a drill to drive a screw in.  The top section of the barn is an 8/12 pitch - so we are screwing down and it's not too bad.  The sides of the roof are very steep, and might be a little more difficult.  Is there a difference in power between the 2?  My Makita's are only 3.0 Amp batteries - I imagine the jump to the 5.2 Festool would be a substantial difference.

I find Phillips #2 and smaller screws prone to stripping, but #3 Phillips screws very resistant to stripping (provided you're using the right bit!).

Festool's 5.2 Ah batteries are 18 V, and they work perfectly with the PDC, so you could buy the basic PDC if you don't require the right angle attachment.

 

[Cheese]

In many cases the impact driver stops before getting the screw in all the way.

A different screw would probably make a big difference - but finding new screws and getting them approved for the project is quite a pain too -and it may not solve the issue.

I'd vote for a different screw thread form. You'd want a GRK or Spax type of point that actually drills its own pilot hole before the thread body enters the wood. Easier on the drill, easier on the operator and easier on the batteries. Actually Timberlok manufactures some screws with the same "drill point" that GRK & Spax use and they also have hex heads which may make them easier to be approved because they look "more normal".

OMG...the amount of political correctness needed for the approval process.

GRK
[attachthumb=1]

Spax
[attachthumb=2]

Timberlok
[attachthumb=3]

 

[Stephen B]

[size=8pt]Too much torque may snap the screws, because you are screwing into old and very dry timber you may need to predrill the holes. Have you tried lubricating the screws with (paraffin) wax or soap? Usually makes a big difference with old timber.

[size=13pt]
I am with Bohdan here, regarding pre drill and some lubrication. My father certainly liked to use soap. As for myself with longer screws such as batten screws, I use an automotive lanolin spray. Pre drill and spray the screw. The use of this product or even grease, some say, in the long term also assists in preventing wood decay around the screw in outdoor structures such as deck supports.

For smaller screws I use soap and also pre drill, particularly in hardwoods. By the way I am using the term hardwood here to mean harder timber. After all Balsa wood is technically a hardwood and it hardly needs lubrication for screws.  [smile]
[size=8pt]
[member=36526]Bohdan[/member]

 

[cblanton42]

[member=13058]Kev[/member]
No, it's not a common approach here in the US, I suspect being a large barn is why it's so different.

CB

 

[Holmz]

In lieu of soap or butter....

I have a little A10M, which looks like a kids drill, but require some wrist strength.


If the Metabo was cheaper to get I would have gotten it as they are 'the same'.

The A18M is the bigger version, and there is a Metabo for that as well as they are in cahoots.
You pretty much want to look at the torque specs unless it is an impact.
Even the little A10M has a lot of torque. 17/34 NM (150/300 inch pounds) on high and low speed respectively.
Maybe the brushless DC motor has a bearing on it?

http://festoolownersgroup.com/festool-tools-accessories/help-with-drill-decision/

Ideally one brings a screw with them and a hard chunk of wood and does the test drive in-situ.
or get one with 450-700 inch-pounds.

 

[Tyler Ernsberger]

PDC. 

That long of screw will give any cordless impact problems, lots of shaft to twist.

I can't sink 9" timber locks with my brushless makita impact or a M18 fuel impact.

My old C12 will even finish off where those two stop.

I like the PDC quadrive plus it has a side handle.

The Festool PDC is the right drill for the job.

 

[rst]

For roof insulated nail base installs the hex head screws are not allowed.  Only a washer/truss head type is used so the sheathing layers are still flat.  This type construction has been common in commercial work forever, mostly for flat roofs and solid foam sheeting with the nail/glue base layer glued to the insulation. Screws up to 12" are available.  I just had my roof redone with 4" of urethane foam nail base and the screws used were 6" GRKs, then weatershield and finally painted standing seam.

 

[Wuffles]

PDC. 

That long of screw will give any cordless impact problems, lots of shaft to twist.

I can't sink 9" timber locks with my brushless makita impact or a M18 fuel impact.

My old C12 will even finish off where those two stop.

I like the PDC quadrive plus it has a side handle.

The Festool PDC is the right drill for the job.

Thirded. PDC worked very well when the Bosch impact couldn't manage.

Drill/driver aside, is this a common US roofing approach? I would have thought the foam would compress over time and create knock on issues.

Same in the UK for flat roof systems these days [member=13058]Kev[/member]. Well, for my building inspector anyway. It's a seriously rigid foam though, foil backed both sides. Look up Celotex or Quinntherm, but you probably have heard of it already now I've jogged your memory.

The un-bonus to this extra mm of foam is that the fixings no longer hold the top material well enough to the bottom material and in the case of GRP roofing you end up with some hilarious noises coming from the expansion and contraction of the materials no longer working in parallel during temperature changes (worst in Summer). Didn't happen then the specs were 50mm insulation afaik.