Joe gave a good procedure. I think why you don't get good exact size recommendations is that every block is different, every drill press is different (runout), drill speeds are different, stroke speed is different, climactic factors are different, different drill sharpness, drill cooling, time between holes for cooling, etc., etc. Way too many factors to say, this or that size bit will work - or even a bit so many thousandths under will work. I do what Joe does. I have about six or seven different sized bits. I'll drill a hole with each (newbies like me don't have a clue as to which will be close). Pound some pins and see where you end up. Pick the one that looks the best and drill and pound a few more with that bit. See how they end up. Because of my newbie-ness (or is that newbie-osity?) I usually do at least a dozen test pins to be sure I am going to be on target. I suppose after one has drilled a number of blocks, you start refining your starting point. I know one rule of thumb is that the more layers a block has, the less the differential between pin diameter and bit diameter. Andre Bolduc recommends a 0.250" bit for a 0.282" diameter pin (I'm going on recollection here - don't beat me up too bad). For a 7 - 11 ply multi lam, you will typically use a larger bit. For a Delignit block with 847 laminations, you will typically find a bigger bit to work well. Old post from Ron N.: That's the way I do it. The first pass is with 1/4", and the second with 17/64, or 6.8mm. That's for Delignit, since the final hole is only about .013" undersize. For a maple block, the hole is considerably smaller and can be drilled in one pass. If you still want to do a two pass drill in the maple, do the pilot at about 7/32". With a two pass system, the type of drill becomes unimportant because chip clearing and bit heating aren't nearly as critical on that first pass, and no problem at all on the second, since you're just doing a final ream to size. I use regular jobbers bits. Here ya go. Here is the answer you were looking for in an old post from Mike Mcoy (the metric conversion is your baby!): Hi all, Our PTG Chapter started a pinblock project in 1996 with 8 different pieces of pinblock, each piece drilled with 10 different size holes and all pinned with number 2 pins, torque readings were then taken on each pin in 1996 and again in 1999. The following is cut/pasted from a Lotus 123 spreadsheet so the columns are off a bit but you can figure it out. If anyone wants the 123 file just ask. No one remembers what type of block number 6 was... oh well. Drill Size Letter Fraction Metric #1 - Sohmer 5 ply Maple June 1996 Sept 1999 0.25 1/4" 6.35 210 185 0.252 6.4 210 180 0.2559 6.5 205 175 0.2571 F 6.53 180 170 0.2598 6.6 175 160 0.261 G 6.63 160 150 0.2638 6.7 150 125 0.2657 17/64" 6.75 148 130 0.2677 6.8 148 130 0.2717 I 6.9 140 120 Drill Size Letter Fraction Metric #2 - APSCO Dilignit - 18.5 PPI Beech June 1996 Sept 1999 0.25 1/4" 6.35 275 255 0.252 6.4 265 225 0.2559 6.5 280 250 0.2571 F 6.53 280 250 0.2598 6.6 280 245 0.261 G 6.63 280 225 0.2638 6.7 275 230 0.2657 17/64" 6.75 265 225 0.2677 6.8 250 200 0.2717 I 6.9 220 185 Drill Size Letter Fraction Metric #3 Baldwin 49 ply Maple June 1996 Sept 1999 0.25 1/4" 6.35 180 145 0.252 6.4 190 145 0.2559 6.5 190 150 0.2571 F 6.53 205 160 0.2598 6.6 175 145 0.261 G 6.63 200 155 0.2638 6.7 180 145 0.2657 17/64" 6.75 180 150 0.2677 6.8 150 140 0.2717 I 6.9 140 110 Drill Size Letter Fraction Metric #4 - Bolduc 5 ply Maple June 1996 Sept 1999 0.25 1/4" 6.35 230 190 0.252 6.4 230 200 0.2559 6.5 200 165 0.2571 F 6.53 220 185 0.2598 6.6 215 185 0.261 G 6.63 190 155 0.2638 6.7 160 115 0.2657 17/64" 6.75 180 150 0.2677 6.8 160 145 0.2717 I 6.9 110 95 Drill Size Letter Fraction Metric #5 Schaff Dilignit June 1996 Sept 1999 0.25 1/4" 6.35 230 190 0.252 6.4 230 200 0.2559 6.5 225 185 0.2571 F 6.53 225 185 0.2598 6.6 215 175 0.261 G 6.63 200 150 0.2638 6.7 205 160 0.2657 17/64" 6.75 200 160 0.2677 6.8 175 160 0.2717 I 6.9 150 135 Drill Size Letter Fraction Metric #6 ???? 14 PPI Beech June 1996 Sept 1999 0.25 1/4" 6.35 150 125 0.252 6.4 145 125 0.2559 6.5 145 120 0.2571 F 6.53 145 125 0.2598 6.6 140 120 0.261 G 6.63 130 120 0.2638 6.7 110 90 0.2657 17/64" 6.75 105 95 0.2677 6.8 80 75 0.2717 I 6.9 75 65 Drill Size Letter Fraction Metric #7 - Falconwood 20.5 PPI Maple June 1996 Sept 1999 0.25 1/4" 6.35 380 340 0.252 6.4 360 325 0.2559 6.5 380 320 0.2571 F 6.53 360 310 0.2598 6.6 350 300 0.261 G 6.63 275 235 0.2638 6.7 380 325 0.2657 17/64" 6.75 380 330 0.2677 6.8 350 315 0.2717 I 6.9 305 250 Drill Size Letter Fraction Metric #8 - Schaff 11 Ply Maple June 1996 Sept 1999 0.25 1/4" 6.35 210 185 0.252 6.4 210 180 0.2559 6.5 205 175 0.2571 F 6.53 180 170 0.2598 6.6 175 160 0.261 G 6.63 160 150 0.2638 6.7 150 125 0.2657 17/64" 6.75 148 130 0.2677 6.8 148 130 0.2717 I 6.9 140 120 -- Mike McCoy So Central Pa Chapter 170, PTG Middletown, Pa Mailto:mjmc@attglobal.net ----- Original Message ----- From: "Richard Brekne" <Richard.Brekne@grieg.uib.no> To: <pianotech@ptg.org> Sent: Monday, May 06, 2002 2:51 AM Subject: Re: Pin sizes was Re: Pinblocks > A440A@AOL.COM wrote: > > > >. In milmeters if you will, how > > >much difference do you all recommend between bore size and pin size > > > > This depends totally on the material that the block is made of. > > Regards, > > Ed Foote RPT > > Grin... now thats what I like.... a bonified half answer :)... So er.... > could you give a few examples then ? > > > -- > Richard Brekne > RPT, N.P.T.F. > Bergen, Norway > mailto:rbrekne@broadpark.no > http://home.broadpark.no/~rbrekne/ricmain.html > >
This PTG archive page provided courtesy of Moy Piano Service, LLC