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I am new to using the Kreg joining system and I see that screws are offered in both coarse and fine thread. Is there a "rule of thumb" to use for making the choice?

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Hi  Daryl. Basically the course screws are used on softwood like pine, ceder also mdf and plywood. The fine screws are for hardwoods like oak and maple. Happy and safe woodworking. Will

Thanks for starting this discussion ! I too am new to using this type of jig and screws, and I was having trouble with the coarse screws cracking the pine boards on the end grain joints. I just happened to run into a fellow jigger in the local "lowes" and he suggested I try using fine thread screws when screwing into end grain joints on pine.  

 

Mike 

Hi Mike, I use fine thread in almost all of my projects as the course screw is pretty agressive by nature of the thread pitch.  In the 20 plus years of building cabinets and furniture I never have had the problem of stripped and cracking wood joints like was discussed at great length a couple months ago.  In the soft wood I just slow down the speed of which I insert them and they cut enough thread in the wood to hold quite well.  In some of the the extream course wood fiber I have added some tight bond brand glue to the screw thread and it acts as a lube as the screw is driven in and then cures into a tight thread system on the screw.  I have found from experience that driving screws is like in the automotive industry.  You have to take it easy when driving nuts and bolts into an aluminum thread and seldom is it advisable to use an air wrench as the final tightening tool.  I also used a product called "never seize" on the aluminum thread.  The glue acts kinda like the "never seize"  The  difference is that "never seize" acted like a lube for the thread and then also prevented the metal from seizing the aluminum thread to the bolt thread.  In the threading of a screw into the soft and course fiber of wood if you over do the speed of insertion and the tightening of the screw you get the stripped threads and the split screw joint. 

Mike Robson said:

Thanks for starting this discussion ! I too am new to using this type of jig and screws, and I was having trouble with the coarse screws cracking the pine boards on the end grain joints. I just happened to run into a fellow jigger in the local "lowes" and he suggested I try using fine thread screws when screwing into end grain joints on pine.  

 

Mike 

Thanks Jay, ...hey, how did you know I was an Automotive tech ? I have worked for the local Subaru dealership for the last 14 years so I can relate to everything you just covered. In 2008 I reached "master Tech" level and last year in 2010 I reached "Grand Master Tech"....now I have slowed down and I am enjoying my time woodworking.

My father was a carpenter....that man could build anything with wood !

Jay Boutwell said:

Hi Mike, I use fine thread in almost all of my projects as the course screw is pretty agressive by nature of the thread pitch.  In the 20 plus years of building cabinets and furniture I never have had the problem of stripped and cracking wood joints like was discussed at great length a couple months ago.  In the soft wood I just slow down the speed of which I insert them and they cut enough thread in the wood to hold quite well.  In some of the the extream course wood fiber I have added some tight bond brand glue to the screw thread and it acts as a lube as the screw is driven in and then cures into a tight thread system on the screw.  I have found from experience that driving screws is like in the automotive industry.  You have to take it easy when driving nuts and bolts into an aluminum thread and seldom is it advisable to use an air wrench as the final tightening tool.  I also used a product called "never seize" on the aluminum thread.  The glue acts kinda like the "never seize"  The  difference is that "never seize" acted like a lube for the thread and then also prevented the metal from seizing the aluminum thread to the bolt thread.  In the threading of a screw into the soft and course fiber of wood if you over do the speed of insertion and the tightening of the screw you get the stripped threads and the split screw joint. 

Mike Robson said:

Thanks for starting this discussion ! I too am new to using this type of jig and screws, and I was having trouble with the coarse screws cracking the pine boards on the end grain joints. I just happened to run into a fellow jigger in the local "lowes" and he suggested I try using fine thread screws when screwing into end grain joints on pine.  

 

Mike 

Well Mike it is a small world. I graduated from highschool in 1961 and  spent about 10 years as an automotive mechanic- machinest where I specialized in building race car engines.  A fellow whom ran a automotive shop in the same town as I did sold out his shop about the same time as I entered law enforcement and opened up a cabinet shop. I used to do machine work for him at the time and after I left law enforcement in 1993 he was still running the same cabinet shop.  I opened up my own cabinet business and again did some custom work for him.  It is kinda interesting to know that you were into automotive repair and now also do woodworking.  Talk about it being a small world and how three of us have our interest running in the same trend.  It must be the technical and creative habits that we have that leads us in the same general direction. 

It was the aluminum air cooled VW's that I really became aware of aluminum threads and the aluminum blocked oldsmobile and buicks that used to give every mechanic fits.  It was these engines and the modified racing engines that caused me to learn about the heli-coils thread repairs.   Twisted a lot of bolts in thoes years and repaired my share of the stripped out threads. 

I wonder how many other members on here have experience in automotive fields.  There is  one other member that I know about that was a mechanic so this makes three of us whom are members.  Maybe we will trade information again, so don't be a stranger.....:-)   

Mike Robson said:

Thanks Jay, ...hey, how did you know I was an Automotive tech ? I have worked for the local Subaru dealership for the last 14 years so I can relate to everything you just covered. In 2008 I reached "master Tech" level and last year in 2010 I reached "Grand Master Tech"....now I have slowed down and I am enjoying my time woodworking.

My father was a carpenter....that man could build anything with wood !

Jay Boutwell said:

Hi Mike, I use fine thread in almost all of my projects as the course screw is pretty agressive by nature of the thread pitch.  In the 20 plus years of building cabinets and furniture I never have had the problem of stripped and cracking wood joints like was discussed at great length a couple months ago.  In the soft wood I just slow down the speed of which I insert them and they cut enough thread in the wood to hold quite well.  In some of the the extream course wood fiber I have added some tight bond brand glue to the screw thread and it acts as a lube as the screw is driven in and then cures into a tight thread system on the screw.  I have found from experience that driving screws is like in the automotive industry.  You have to take it easy when driving nuts and bolts into an aluminum thread and seldom is it advisable to use an air wrench as the final tightening tool.  I also used a product called "never seize" on the aluminum thread.  The glue acts kinda like the "never seize"  The  difference is that "never seize" acted like a lube for the thread and then also prevented the metal from seizing the aluminum thread to the bolt thread.  In the threading of a screw into the soft and course fiber of wood if you over do the speed of insertion and the tightening of the screw you get the stripped threads and the split screw joint. 

Mike Robson said:

Thanks for starting this discussion ! I too am new to using this type of jig and screws, and I was having trouble with the coarse screws cracking the pine boards on the end grain joints. I just happened to run into a fellow jigger in the local "lowes" and he suggested I try using fine thread screws when screwing into end grain joints on pine.  

 

Mike 

I would never question Jay, he is a great woodworker.  But I always use coarse thread in hard and soft woods.  I have never had any trouble with splitting.  I do also put glue on my screwsbefore i install them.
Wow talk about being confusing. What is a woodworker to do? Try every configuration and see what works. I guess that's what makes woodworking an art not a science.
Will, truer words were never spoken.  It is an art and what works for one does not work for others or at least not in the same fashion.  Every person has a way of applying each method.  The biggest thing is patience and the belief that it can be done.

will delaney said:
Wow talk about being confusing. What is a woodworker to do? Try every configuration and see what works. I guess that's what makes woodworking an art not a science.
 I also believe if you study your grain pattern in the end of the wood sometimes you can advoid splitting. I also go slow sometimes we woodworkers get too excited when everything is coming out right. We tend to hurry a bit.

I agree with you I also have better luck with putting glue in the wholes especially when working with softwood.

Even it the whole strips out the glue keeps the screws in place and lubricates the screw as it penetrates. 

Michael Campbell said:

I would never question Jay, he is a great woodworker.  But I always use coarse thread in hard and soft woods.  I have never had any trouble with splitting.  I do also put glue on my screwsbefore i install them.
Wow, this is all great feedback. Thanks for all the information!

I know I'm late to the discussion, but add one more with an automotive background...I own an automotive reconditioning business.  We do cosmetic repairs like fix a cracked bumper and repaint it, or fix tears in leather seats, stuff like that - no mechanical work, no frame pulling (collision repair) just basic cosmetic stuff.  I have had the kreg jig for almost 2 years now and sadly haven't used it yet - probably a product of owning my business.  But I'm expanding my shop and I've decided that rather than buy desks for my inside sales reps, I'm going to build them using the kreg jig.  Then after I've built them (out of poplar and birch) I'm going to build mine out of oak - so the discussion regarding which screws to use for the soft wood and the hardwood - as well as the additional tips of being able to use fine for any as long as you go slow, lube the screws with glue, and pay attention to the grain seems like it makes sense and will probably be a big help to me as I get going on this project.  Thanks for the info guys!

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