Tapping Real Deep How?

[Cartierusm]

I'm making a fixture to adjust a video camera side to side, it won't be moved very often. I'm using a dovetail plate and a bearing in the main housing and moving the dovetail plate side to side with regular 1/4-20 threads. I don't know if that will work for linear motion but it doesn't need to move very often as I said. The plate is 2" deep. The question is how do I tap that deep, I can reach both sides but that wouldn't work because they wouldn't meet up and they wouldn't be long enough either. So how do a make a thread 2" deep? Or should I machine a recess hole 1/2" deep on both sides that the tap can fit in and then just basically tap the inner most meat of the plate?

[GaryCorlew]

I think these might work for you, not cheap though
http://www.michigandrill.com/part/?p=72751

[Andre' B]

You can get pully taps that would work.

But the longer the mating threaded parts the closer the thread pitch of the male and female parts must be or things bind up.
So making a C'Bore from each side and just having a shorter threaded section would be a better design.
And nothing wrong with a deeper C'Bore from just one side.
And if it lets you use a more standard tool then all the better.

[Geof]

Originally Posted by Cartierusm ......Or should I machine a recess hole 1/2" deep on both sides that the tap can fit in and then just basically tap the inner most meat of the plate?

Yes, that is certainly the easiest. Actually don't even bother going to the middle from both side, drill a clearance hole 1-1/2" from one side and then tap the remaining 1/2" from the other.

Better yet, in my opinion, get a thread insert of the type that has a standard thread on the OD and ID; I think 1/4-20 inside has 3/8-16 outside. Then you drill 5/16 all the way through, tap 3/8-16 for the length of the insert and screw it in. The insert will last much longer than the thread in aluminum and is much less likely to gall up.

[Cartierusm]

Geof, that's what I was continplating last night while I slept, thanks for all the help everyone.

[Geof]

Originally Posted by Cartierusm Geof, that's what I was continplating last night while I slept, thanks for all the help everyone.

I wish I could do that, when I am asleep I am totally beyond any contemplation; perhaps you mean 'while I couldn't sleep', that is a condition with which I am very familiar.

[Cartierusm]

Oh I don't sleep, I'm a real insomniac, but when I do sleep, usually during the day on the couch my brain has a way of working things out. Honestly that's probably why I can't sleep too much rolling around up there.

Don't know where you are but it's DAM HOT here today, San Francisco. BBQ Time.

[Geof]

Originally Posted by Cartierusm ....Don't know where you are but it's DAM HOT here today, San Francisco. BBQ Time.

Vancouver, just a few hours north and it is warmish here. I am taking a break from digging (by hand) a 200 feet long ditch across the back of my property. A good way to lose weight and get fit and it helps with the sleeping at night.

[Cartierusm]

Dam, that's hard work. Why the trench? Plumbing Issue? You should have rented a back hoe, then added servors to control it, see there's always a new use for Mach3.


P.S. Geof, what type of threaded insert would you recommend from McMaster, http://www.mcmaster.com/#=3eivrk

[Geof]

This page the middle top: http://www.mcmaster.com/#threaded-inserts/=3ej0ms

Click and it will take you to more detail and there is a version with a nylon insert.

The ditch is a perimeter drain around my property. My wife and I live on an island in a river delta just south of Vancouver, Richmond actually where the Vancouver airport is. We have 1-1/2 acres surrounded on three sides by agricultural land so it is like living in the countryside but in winter we get a lot of standing water so I am putting in the drain to intercept surface flow from the neighboring properties. So far I have done just under 800 linear feet about 10 inches wide and 24 inches deep and have about 400 to go. I can't get in with a backhoe because of trees and gardens and buildings but anyway the exercise is good for me. I passed a major cardio test a couple of years ago with flying colors, cholesterol is good, good lipoproteins are high bad ones are low and five minutes on the treadmill hooked up with dozens of wires produced the correct kind of trace on the machine. I plan on keeping it that way for a few more years; I reckon I am doing pretty good at almost 66 and not on any heart drugs.

[Cartierusm]

Wow, that is good, better than me probably and I'm 36. Well good work. If I was around I'd help. I haven't been to Canada in a while.