Index Pin Accuracy on Line Boring Machines

Index pin setups let you extend the line of holes you bore, but there is debate about how accurate they allow you to be. October 2, 2007

Can someone please help me understand the benefit and application of indexing pins on line boring machines? I'm finding that some of the units I'm looking into reference them and some do not. How important are they and is there any type of "mounting" that we should stick to?

Forum Responses
From contributor P:
Indexing pins allow you to extend the drilling line for, say, drilling a closet partition or tall cabinet, instead of having a long fence with dedicated stops. I think consensus has it that the actual stops, properly set up, are ultimately more accurate than an indexing pin system, but the pins do fine for most work. Obviously, some method of extending your drilling beyond the first set of holes will be critical.

From contributor R:
From my experience, index pins are a waste of time. They are not particularly accurate.
I concur with the poster above that stops are preferable.

From contributor P:
Pins work fine for me - I haven't got the space to devote to a fence system, as the boring machine sits between two workbenches and long work has to overhang them.

From contributor F:
Contributor P, which machine are you using? I have a Delta and I haven't even tried using the indexing pins yet!

From contributor P:
Ritter R-46 - pneumatic pins.

From contributor R:
When using the pins, did you ever measure with a caliper the distance between the holes? I know with my old Conquest, I was always off.

From contributor P:
I need to make sure that the pin is coming straight down into the reference hole. Otherwise, I can shift it a bit in either direction. Usually I'm only extending a line for tall cabinets, so won't be devastating if it's off a bit - shelf pin holes only.

From the original questioner:
Thank you for your responses. I really appreciate the help. But just to clarify, are you stating that if the drilling machine has the extension ruler/fence on it, I don't need indexing pins and vice versa?

From contributor R:
The short answer is yes. Again, if you need dead on accuracy, go with the fence and stops. I also found the fence and stops to be quicker.

From contributor H:
I have a Detel machine and the index pins are not as accurate as the fence stops. The trick to setting up repeatable stops is to use a stick that is in 32mm increments that you insert between stops to register them accurately. This way the holes will always continue in 32mm increments.

From contributor B:
As an alternate viewpoint - I've never had a bit of trouble with index pins on my dual head lineboring machine (Conquest 46). I have however, as a rule, had plenty of trouble with stops - they get slammed out of position, or someone moves them and forgets to set them back, etc. I'll choose index pins for reliable repeatability on a lineboring machine any day. If you are having a hard time finding the index pin when setting up for the second bore, just put a mark on your fence where the bottom of the panel is when the pin is in place. This should help you slide the panel down to the right neighborhood, then raise the pin, to lock the panel into precise position. If your find pin is locating in a wrong place, you might call your machinery dealer and ask them to adjust it.

From contributor O:
We have the double line Conquest and use the second set of stops along with the indexing pins. Works great for us - just drop the stop, slide piece down, and raise the pin. May have to wiggle the piece to get the index pin to fall solidly into the hole, but seems quick and reliable.

From contributor J:
The Conquest or the Detel work very well and are very similar. Conquest is less money and made in the US. I have always been told upstroking machines are more accurate and seem to be less money. The pin stops are a little tricky, but if you mark the fence for the first move, then put the flip stop there for reference, the next time it is very easy and accurate.