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Thread: Interapid Repair
04-18-2013, 07:36 PM #1
My favorite Interapid 311B-1 took a hit to the side of the indicator tip, not very hard but when it was handed back to me the tip wasn't moving very well and it seemed jammed. I started fiddling around with the screws and it started to free up a little. It's still sticking and I can't seem to get it to work, and can't get it back to zero. I don't think I can send this out for repair, lack of parts would be a problem. Does anyone have any experience taking one of these apart? I took the 4 screws out and I can see a little of the mechanism but not sure how to get inside this thing. There is two screws on the back of the dial?
04-18-2013, 08:07 PM #2
Check out 027 : Long Island Indicator Service : Sales, Repairs and Spare Parts - their web site says that they repair many different indicators. They list Interapid for some instruments, and not for others. Send them an e mail - if they don't repair indicators, they probably know who does.
04-18-2013, 08:14 PM #3
04-18-2013, 08:21 PM #4
Another vote for Long Island.
About 20 years ago, I was a kid. My boss was trying to introduce me to a Bridgeport.
He was out for a bad back, and I was experienced enough to think I could borrow his Interapid.
I somehow turned the spindle on with his indicator in the spindle. I learned that they won't survive 100mph hits to the wall.
Long story short; Long Island Indicator fixed that Interapid before the doctors could fix a back, and I'm still machining.
04-20-2013, 10:16 AM #5
04-20-2013, 11:02 AM #6
So does anybody know how to take these apart ? I don't need to repair them, but sometimes we get coolant in them, and I would like to be able to clean them.
I know, there are many ways to keep that from happening, but sooner or later, it happens.
I get the 4 screws off, and I'm not sure where to go after that. If it takes special tooling, does anybody have a source ?
04-20-2013, 11:21 AM #7
04-20-2013, 11:29 AM #8
04-20-2013, 11:36 AM #9
Especially if it was your brother! lol. When this happened to me, the guy that borrowed it didnt ask, he just took it, and then turned the spindle on at 8k. Not sure how far up the RPM ladder it got before it flew off, but the dent is still there where it hit the side door of machine. He was nice enough to offer to cover half the cost of repairs with me though, so that was ok I guess.....I was mad as hell at the time though. I still have it as a testament to the beating an Interapid can take at still work (I dont trust it for fine work though).
04-20-2013, 11:46 AM #10
04-20-2013, 05:28 PM #11
I fixed a 312B-1 that an operator jumped the gears on. It was jammed up tight and what little movement it did have made a horrible noise. He didn't want to pay to have it repaired and considered it a loss so he let me have a go at it. First of all, do not take the bezel/gear assembly off the main housing. Setting the preload on that spring was one of the hardest and most frustrating assemblies I have ever done - right up there with a Winchester Model 88 lever action. I would suggest maybe a little electrical contact cleaner - something that evaporates very fast and clean, and some canned air for cleaning computers. The gears and springs inside are extremely delicate, don't open unless you are prepared to either toss it or send the mess to a professional.
04-23-2013, 01:48 PM #12
I fixed an 312B using a part from another nonworking 312, once. If you must take that assembly off, I recommend using some scotch tape and lightly tape the needle to the face of the indicator during removal, so it can't turn (glass/plastic crystal removed, of course). Makes reassembly much easier.
From what I remember, the gear will have to turn a little in order to mesh with the arm upon reinstallation, hence using the tape "lightly"
04-29-2013, 03:02 PM #13
Disassembly of Interapids
To get at the internals the dial assy needs to be removed, removing the side screws is not recommended, the adjustment on those screws is critical to the proper functioning of the indicator.
To start: the bezel / crystal assy unscrews counter clockwise, you use a small screw driver or the like to hold the bottom base and unscrew bezel by hand placing the driver so the edge rests against the ind body as a positive stop allowing you to put some torque on the bezel. there are notches in the lower plate to facilitate this, after bezel is off the 2 screws under dial assy will allow removal of base plate, as someone suggested tape will hold the zero position, but it's no big deal to reset.
Resetting Backlash spring:
Holding the assy in your left hand put the tip of your right index finger on the crown gear and roll forward (towards your left hand) depending on finger length watch the dial till both hands are zeroed, (hand should be moving counter-clockwise with the small hand to the right for reference) normally you will go around past zero at least twice for the proper backlash spring tension, The test is weather you have equal pressure when depressing contact point in both directions, it should be very close.
If cleaning the dial assy the hands and dials need to be removed and very carefully I should point out, the pinion is very thin and easily broken if not done properly with 2 hand priers and equal pressure . Wiha sells chip removers that work very well for the large hand (#26810 $6.10-Digikey). The small hand is removed by first taking the dial screws off and placing an exacto blade under dial adjacent to the hand and twist blade handle to lift up on dial and it will pop off, hold a finger over hand so as not to send it flying. The Exacto is also useful in removing the screws as they are really tiny even with the smallest Precision driver.
Cleaning should be done in an ultrasonic cleaner in a jar with denatured alcohol, being careful not to leave it in for too long as the paint is easily removed, you can also dip into alcohol and then blow out with compressed air, when cleaning the dial assy use very light air pressure and the hand temporarily installed and held so as not to damage hair spring (high pressure air will blow the spring out making further repairs necessary. Once cleaned lubrication is necessary.
Lubrication, dial assy:
Spraying some Wd 40 on a block or any hard surface and dipping the tip of exacto to place "minute!" amounts of oil on each bearing/jewel top and bottom, the lower center pinion (large hand) bearing is above the crown gear and also needs lubrication its a little hard to get to but the tip of the blade can reach it.
Lubrication, main body:
Lubing the body bearings is done in the same manner, you can put excess in and blow out with compressed air. If the bearings are out apply a lot of WD40 into the ball bearing assy with a small diameter test indicator contact point mounted in a hand drill press against the roller cage and spin at a fairly high speed then reverse, rinse with fresh WD and repeat, blow out the bearing with compressed air and that will be sufficiant.
Adjustment of the bearings is critical,the sector gear must fall freely when raised to the middle position under its own weight, in addition to having next to none side to side play, the same goes for the lifting mechanism (side play) of the contact point assy, that's why I say to leave these bearings alone. But if they have been touched, leave one side locked and snug and tighten the opposite side then. back off just enough to allow movement,remember tightening the locknuts will also tighten the bearings so you need to loosen enough to allow free movement after tightening, you can check play with tweezers inside the body assy.In addition the gear sector and cam assy inside the body need some clearance from each other, not a lot just not touching.
When re-installing the dial assy, wind as described above and hold indicator hand with your finger at the 12 O'clock position, then you must lift the sector to the middle position by depressing the contact point from above, it requires very little pressure to get it in that position, and you will feel a positive stop before cam lifts it to the upper position , you will know when done correctly if you depress point in both directions and you have equal range and it returns to zero. A few tenths of inequality is acceptable being it's past the workable range of the indicator.
If the hands have been removed the starting point for setting backlash tension is around a finger length, that is rolling the crown gear from finger tip to the second knuckle around 2" the hand should be going counter-clockwise, holding position with the small hand to the right, the small hand does not need to be installed now just for reference.
After assy check for equal pressure top and bottom and adjust backlash accordingly SLIGHTLY more or less depending on the situation.This can be checked without installing the screws that hold the dial assy on, just hold it in place and test.
Because of the way interapids are made and the shape of them,the proper way to check accuracy is with the contact point adjusted parallel to the bezel assy, normally I hold it up to a window with blinds on it and use the slats as a reference holding the body so that the bezel is horizontal and bend the point accordingly.
Any questions feel free to shoot me an email
Last edited by precrepair; 04-29-2013 at 07:26 PM. Reason: runon sentence
04-29-2013, 03:23 PM #14
It is really nice of you to write such a detailed description. But it is almost impossible to read as it is, please remember to add a carriage return now and then when typing long paragraphs. Just a bit to help break up what you are saying so it is easier to read.
Thanks again for your effort.
04-29-2013, 06:22 PM #15
04-29-2013, 06:28 PM #16
That was a heroic effort on an iPhone!! Thanks.
You really use WD-40 in that application?
04-29-2013, 07:48 PM #17
Yes, have been using it for 30 years, Ive tried all oils, watch, clock you name it none work as well as WD same goes for micrometers the trick is use it sparingly it takes very little to lube a bearing or a spindle just a light coat, on mics I apply it run it through a couple of times then clean the female threads and then remove it from the spindle with mop string, it leaves the perfect amount on and they run like glass
04-30-2013, 02:46 AM #18
WD-40 is paraffin in a volatile carrier. It's not designed nor intended to be used as a lubricant.
04-30-2013, 06:11 AM #19
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04-30-2013, 08:43 AM #20
I have to agree, quite an effort on an iPhone. Besides writing well, precrepair also does excellent (and less expensive than some others) repairs, another satisfied customer.
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