Stern Rail Seats - Follow Up

[tgrass462]

Well this weekend my son and I spent about three hours positioning our newly received Stern Rail Seats (from Hunter - about 7.5 Boat Units) on our H-26 #174. Surprise - Surprise - we were drilling the 11/64" diameter holes to prepare for either attaching backing plates (as we were told that boats earlier than hull number 255 or so did not have backing plates glassed in at the factory) and/or to prepare to drill out the 1/2" diamter holes for the toggle bolts when we found aluminum shavings coming from the fiberglass! We have backing plates after all!I drilled all the holes through the aluminum ... now next weekend I'll be tapping 1/4" threads. Any suggestions on tapping aluminum threads? I know you have to go slow - and not break off the tap - but do you use any cutting oil? WD 40? 3 & 1 oil? I've never done this ... any suggestions would be great.Regards,Tom GrassGrasshopper IIH-26 #174

 

[boboduke]

Tapping Aluminum

A 1/4" tapped hole in aluminum is rather easy to do. You will need some lubricant, 3and1 or wd-40 is fine. Just start the tap and for every 1/2 turn you make, just back it off 1/4 turn to break the chip that is formed. The most important part is to make sure that you are going in straight since aluminum is soft it is easy for the tap to go crooked. If it starts to get to hard to turn, just back the tap out and clean out the chips and add more oil.

 

[Luke]

tapping

When tapping the wholes in our 216's aluminum boom we used WD-40 for lubrication. The drill we used was low speed and reversable. The procedure was...1.We sprayed WD-40 in the inside walls of the whole.2.We GENTLY pushed the tap through the whole with the drill going slowly.3.We put the drill in reverse and pulled it out slowly.  Good Luck Luke

 

[tgrass462]

Follow-Up

Last Saturday - my future son-in-law and I spent about three hours:1. Redrilling the holes from 11/64" dia to 7/32" dia2. Tapping by hand the 1/4" x 20 threads - using 3-in-1 oil as a lubricant3. Placing the SRS into position 4. Putting some 5200 sealant on the flanges5. Bolting them into position.Thanks for everyone's help.Tom GrassGrasshopper II94 Hunter 26 #174p.s. Hopefully in about two weeks - putting into the water at Kenlake Marina - Kentucky Lake!