Is there a Torque setting for rail bolts? Or are there two many different attachment methods to list a torque spec. I hope I'm not giving wrong info here but I think my rail bolts are 1/4" course thread with crowned washers with slots I'm assuming are to aid in biting into the slate. I was going to cancel this post until I could verify the bolt size but didn't see that option. I erased the text but the thread was still there so hit the undo button and here it is.
Torque specs for Rail Bolts
- Thread starter whittle
- Start date
Are they t-rail style or do they go down throught the slate?
Hard Knock Cues
Well-known member
Although I'm still considered an amateur table mechanic I have a lot more experience in construction.
I'm thinking the cupped washers act like a lock washer and maintain pressure on the bolt so it doesn't loosen with vibration. Your flat washers may allow the bolts to loosen over time. Let us know if that happens in the future.
Robert
Why?
I forgot to specify that I also put spring washers on the square plate, we had problems with the cup washers, the edges of these washers are sharp and they cut and eat the wooden slate reinforcements in wood pine and that's where the rails fall loose.
I'd also speculate that when you see the washers start to flatten, if that's possible, you've achieved the required clamp load and you're not going to get anymore clamp till that washer is completely flattened. At that point you're in the danger zone. Plus the washer is damaged.
Again, I'm just speculating.
Rail bolt torque is all based on what is used as the anchor attachment. T-nuts won't hold up to 15ft lbs, the Diamond threaded inserts and the Brunswick capture nuts will. The flat washer tapped threaded anchor plates that are held in the bottom of the rails with 2 or 3 wood screws won't hold more than 10ft lbs. So the size of the bolt has nothing to do with the torque, it's the anchor that determines the torque.
Strong hardwood laminated rails put more uniform pressure on the slate too, than 1 5/8'' poplar cheap rails. With large square washers at 10ft/lbs that begining to tight solid, I stopped it to 12ft/lbs and I'm sure that's really enough. It's more dangerous for the slate to tight more cheap rails than a very strong one, cheap rails put more a curve pressure on the slate than rails rock solid one, these ones put a more uniform flat pressure on the slate. My considered opinion!
Poplar is a hardwood and I'm pretty sure Gold Crown rails are made from Poplar, but I could be wrong.Strong hardwood laminated rails put more uniform pressure on the slate too, than 1 5/8'' poplar cheap rails. With large square washers at 10ft/lbs that begining to tight solid, I stopped it to 12ft/lbs and I'm sure that's really enough. It's more dangerous for the slate to tight more cheap rails than a very strong one, cheap rails put more a curve pressure on the slate than rails rock solid one, these ones put a more uniform flat pressure on the slate. My considered opinion!
What I've read is that Poplar is chosen for rails because when staples are pulled, the holes tend to close up.
In other words, Poplar can handle more re-coverings.
I'm thinking Poplar was chosen when Tacks were used. Maybe its not that important with staples.
Do I have it wrong??
Poplar is used as harder woods will not accept staples as well and tend to chip out or crack unlike poplar. Even Diamond still uses poplar at tye area where the cloth is stapled but uses other Harwood on the rest of the rail.
I think Rasson uses a small strip of wood on their rails which is probably poplar
I think Rasson uses a small strip of wood on their rails which is probably poplar
Exactly, poplar is one of softest hardwood and accept staples, don't need to laminate glue a softwood strip on, like on the very hardwood rails, and this is a less expensive method to make rails.
Hard Knock Cues
Well-known member
We use popular a lot in the construction business, mostly for trim because it's a stable wood also
Probably poplar is stable as you say, but I believe that a simple piece of non-laminated wood is really not the best thing for making rails, here we have 21 tables that are at least 35 years old. several rails are no longer straight and often a little bit too much to be acceptable. Currently I am building a very solid chassis to machine all these rails, put them perfectly straight, it is a very solid beam in cold roll steel where the rail will be fixed with 5 bolts and 2 other beams which them will support bearing rail guides for a router in order to take light cuts on the rails to straighten them, this whole kit will be in the 0.001'' precision, I will post photos of that soon. That gives me 126 rails to straighten and then redo the 252 angles of pocket, a good job, but I'm setting up to be efficient.
I may add the large flat washers and cup washers on my table rails as you mentioned. My rails are oak and the table frame is oak but the wood glued to the bottom of the slate is a veneered panel made up of strips of wood, unlike plywood where the core is veneer and layed up in alternating directions. This is actually strips of solid wood appx 5/8 thick with veneer on each side. That got wordy but don't know the name of it and hard to describe if your not familiar with it. I said all that just to say this is also soft and I can see the cupped washers digging into it and the rails getting loose.
You're right.