20 replies to this topic

[ropon]

A friend recently had his controller sent in for an adjustment. When it was returned, the contact button was replaced with an oilite. It made the trigger action very rough and because of the location of the oilite, there was no contact with the resistor/wiper was at the center of the trigger pull. Workmanship is one issue but has anyone else had an oilite used as a contact button?

Manufacturer purposely omitted.

[Sloter]

Pictures please.

 

Bob

[Dave_12]

I can't imagine a oilite as being a good conductor plus it would collect dirt very easily  because of the porous nature of oilites.  

[MG Brown]

The wiper button for the Parma controller sort of looks like it could be oilite but IIRC, it's probably a Molybdenum-Copper Alloy pressed into shape.

 

 

Sometimes the new buttons need to be re-shaped for best contact and smooth operation. This depends on the type of controller that you have; electronic, resistor, etc.

It is somewhat of a lost art being able to tweak the wiper arm and button so that it feels just right.

 

[rmjlmartin]

I recently picked up a used Third Eye Hitman that had a 1/8" oilite installed as a wiper button. I have no idea what the controller's history was, so I have no idea when or why it was done. It was set up so that it was contacting the resistor over the full trigger pull, so it was fully functional, but the trigger pull felt very rough. I probably could have worked on it and got it a little smoother, but I just replaced it with a Parma button.

 

The oilite material is obviously conductive enough to work, and assuming that it's smoothed out and adjusted properly, it would probably be ok, but I don't know what the benefit would be. Maybe because it has a flat surface, rather than the slightly rounded face that a lot of wiper buttons have? It would seem to me that would be best suited to a printed wiper board (pwb) rather than a rounded resistor like Third Eye uses, though.

[Bill Seitz]

Electrical contacts that provide some wiping action, like controller wiper buttons and motor brushes, typically are compressed metal powders, usually copper and carbon. Carbon is used because it's both electrically conductive and has lubricity. Carbon content depends on the hardness and degree of lubricity desired, while more copper increases conductivity. An oilite has neither copper or carbon. It's made from much harder sintered bronze usually which doesn't have as good conductivity as copper or the lubricity of carbon in the mix. I'd expect there's no way an oilite bushing will make a smooth wiper contact even with some burnishing. Someone obviously thought they were upgrading this controller or had no supply of wiper buttons, but this isn't a good substitute. A motor brush would've been better, though the usual Parma-type button appears to have a higher copper content and larger surface area, so would therefore offer less electrical resistance. Wiper electrical resistance is typically not a huge concern in electronic controllers because the current in the control circuit is low.

 

I've not used anything other than the standard Parma wiper button. I have experimented with these in recent months and find they are much smoother on both wire-wound resistors and PWB designs if the slightly domed  shape of the button is filed/sanded flat and smooth. For some reason, the smaller contact area of the domed shape is less smooth, my theory being it increases the contact pressure and is able to "fall-into" the gaps between the PWB bands or wire turns. For similar reason, the wiper arm needs to position the button flat against the resistor or board. Smoothness and contact are also compromised if the wiper arm is twisted so an edge of the button is all making contact.

 

It's imperative with both resistors and PWB's that proper mechanical alignment is assured to be in the same plane as the wiper. Otherwise, the wiper can lose contact with the board or resistor over parts of the stroke unless extra wiper pressure is applied. More wiper pressure to assure contact reduces smoothness.

[Jim Difalco]

A friend recently had his controller sent in for an adjustment. When it was returned, the contact button was replaced with an oilite. It made the trigger action very rough and because of the location of the oilite, there was no contact with the resistor/wiper was at the center of the trigger pull. Workmanship is one issue but has anyone else had an oilite used as a contact button?

Manufacturer purposely omitted.

 

Since the quote says there was no contact in the middle of the wiper arm  and the center of the pull it does sound like an actual oilite was used for the contact button.

 

If it is an electronic controller you do not need much contact area on the bands. A wide contact area just means more drag. Take some 800 grit sandpaper and face it towards the wiper button and work the trigger back and forth to get a smooth face. Then blow off any brass dust to prevent grit from causing any roughness. Or just replace the button.

 

Why won't you name the maker who did this repair?

[ropon]

Didn't name the manufacturer because we're more concerned with finding out if this is being considered as a new contact piece by other repair/manufacturers, not to place blame anywhere.
We changed the entire wiper with the oilite and replaced it with another wiper arm with a button from another controller from the manufacturer. The oilite was soldered on so high on the wiper arm that only about 1/16th of the button was touching the wiper/resister at the beginning and end of the movement. At the center position, it was too high to make contact with the wiper/resister.

[Jim Difalco]

If is is an electronic controller then you do not need much contact. Not touching in the center would be more of an issue for me. An oilite will be harder than the copper on a circuit board so wear in the future would also be a concern.

 

Unless you are running a floating wiper button design it is impossible to keep a big perfectly flat wiper button surface from always staying flat on the wiper bands. As soon as you pull the trigger and put side pressure on the trigger it will cause the wiper arm to change it's angle and lift the bottom of the button off the wiper bands. This gets even worse if you are not set up with ball bearings on the trigger pivot to keep the trigger play near zero. I use a very small rounded wiper button contact so even if you get side pressure on the trigger you will not lift the button and cause a massive change in the wiper band you are trying to select for your turn.

[nicky 65]

just to give everyone a heads up..............Howard from Third eye was using oilites as wiper buttons for a while...........I have 3 third eye controllers  and 2 have oilites. They work fine for me.

All of the new Third Eye Controllers have Parma wiper buttons.

[NSwanberg]

Only thing I can think of is that the oilite might be easier to solder to the wiper arm?? I would think it would wear the contact surface really fast.

[Phil Hackett]

Slick7 had contact buttons that had silver contacts bonded to a copper backing (where it was soldered to the wiper arm) years ago. Don't know if Rudy still has any more.

[Bill Seitz]

It's quite possible with some careful work to make the trigger stable enough that there's no sideplay or flex in normal use. I used the rounded/domed buttons for years, found they provided no better contact over the wiper travel than a flat button, and after much experimenting, found flat buttons are much smoother. I discovered that Parma triggers are often thicker than 2 ball bearings leaving an internal space between them. This leaves the inner bearing races unsupported so that when the trigger retaining nut is tightened, the inner races are forced into misalignment creating drag in the bearings. The trigger thickness has to either be reduced or an internal spacer inserted to support the inner races internally and prevent the misalignment occurring. Otherwise, the retaining nut must be loosened to relieve the drag, and this leaves the trigger with sideplay. Carefully fitted trigger oilite bushings can actually yield a better functioning trigger in some cases. I haven't teated any of the other brand triggers to see if the ball bearing fit is better, because I'm weird and don't like them.

 

Third Eye uses a resistor which is smaller diameter than Parma, and without a flat side. The wiper moves in an arc, and this smaller resistor diameter creates some challenge for keeping the wiper button on the center axis of the resistor. I can see where a larger diameter button might be advantageous on a Third Eye, and an 1/8 oilite may be just that. Otherwise, I expect the harder material to cause more wear, though a smoother finish as Jim Difalco suggested will help. The Slick 7 buttons were also larger than Parma and might work better than an oilite. I've still seen them around, so a little digging might turn up some.

[team burrito]

Why would anyone use an oilite for a wiper button?

[wizardgm]

Unless you are running a floating wiper button design it is impossible to keep a big perfectly flat wiper button surface from always staying flat on the wiper bands.

As soon as you pull the trigger and put side pressure on the trigger it will cause the wiper arm to change it's angle and lift the bottom of the button off the wiper bands.

This gets even worse if you are not set up with ball bearings on the trigger pivot to keep the trigger play near zero.

I use a very small rounded wiper button contact so even if you get side pressure on the trigger you will not lift the button and cause a massive change in the wiper band you are trying to select for your turn.

Left handed drivers have it worse, as they tend to 'naturally' reduce the pressure on the wiper due to their finger motion.

I recommend that ALL left handed drivers, should use ball races in their trigger, no matter what manufacture.
 

[Jim Difalco]

It's quite possible with some careful work to make the trigger stable enough that there's no sideplay or flex in normal use. I used the rounded/domed buttons for years, found they provided no better contact over the wiper travel than a flat button, and after much experimenting, found flat buttons are much smoother. I discovered that Parma triggers are often thicker than 2 ball bearings leaving an internal space between them. This leaves the inner bearing races unsupported so that when the trigger retaining nut is tightened, the inner races are forced into misalignment creating drag in the bearings. The trigger thickness has to either be reduced or an internal spacer inserted to support the inner races internally and prevent the misalignment occurring. Otherwise, the retaining nut must be loosened to relieve the drag, and this leaves the trigger with sideplay. Carefully fitted trigger oilite bushings can actually yield a better functioning trigger in some cases. I haven't teated any of the other brand triggers to see if the ball bearing fit is better, because I'm weird and don't like them.

 

Third Eye uses a resistor which is smaller diameter than Parma, and without a flat side. The wiper moves in an arc, and this smaller resistor diameter creates some challenge for keeping the wiper button on the center axis of the resistor. I can see where a larger diameter button might be advantageous on a Third Eye, and an 1/8 oilite may be just that. Otherwise, I expect the harder material to cause more wear, though a smoother finish as Jim Difalco suggested will help. The Slick 7 buttons were also larger than Parma and might work better than an oilite. I've still seen them around, so a little digging might turn up some.

I agree with most of your posts Bill but not here. I have never used a spacer between any ball bearings to support the races. The ball bearings should not get misaligned as the two surfaces of the trigger should be parallel to each other. Having said that I just bought 10,000 nyloc nuts that I use on my trigger pivot from a certain manufacturer as I was having extreme issues with getting acceptable ones. I was buying nyloc nuts that either had too large a hole in them to grip the trigger screw or had the nyloc insert not centered over the hole which would cause the nut to go on crooked and then cause the ball bearings to bind up slightly. I still throw out an occasional nut when it behaves like this during final assembly.

 

The point of the rounded button is to not having variance in the contact location when a perfectly flat button might be contacting at the front edge or the middle or the rear edge depending on the flex in the trigger. While a controller may look like you are getting a full contact patch over a perfectly flat button face you are actually only getting perfect contact when you release the trigger when it goes to brake and the trigger does not have any side force on it. At least on a rounded trigger with a small contact area there is little change in the wiper band chose. Even though I use a round button I do sand a small flat face into it during final assembly.

 

One of the bigger issues are triggers with a sloppy 1/4" hole for the bearings. My bearings press fit into the holes and I have a jig to assemble the bearings with a nut that drives the ball bearings into the trigger. All other triggers, especially Red Fox, have pivot holes that are too large or the bearings pop in easily and you can grab the trigger and put side pressure on them and the trigger will slide back and forth or at least let you induce movement of the trigger and the wiper arm angle.

 

I do not recommend Slick 7 silver buttons. The silver is way too soft and if you get any grit or arc on the wiper bands you will cause a groove to form in the face. Less likely with electronic controllers than the old external resistors , of course.

 

Wow, just proof read this and it sounds really nerdy but it is my business so I hope you will forgive the nerdiness. It that a word?

[Kirbert]

IMHO:  The ideal way to fashion a wiper for a Third Eye would be to use a motor brush mounted on its side and soldered to the wiper arm.  This would create a contact area that was flat and rectangular.  Done correctly, it would wipe smoothly over the barrel shape of the Third Eye resistor without "climbing up" the resistor on either end.

[Bill Seitz]

For years, I never used an inner spacer on my trigger ball bearings. In fact, I didn't use trigger ball bearings for sometime because I discovered a carefully fit set of bushings actually resulted in smooth operation with less sideplay than the ball bearings. No amount of adjusting the screw and nut took out all the sideplay without binding the ball bearings, so I began investigating why this was. That's when I realized that, at least with Parma triggers, there was an internal gap between the ball bearings that allowed the inner races to be forced out of alignnment when the retaining nut was tightened enough to take out the side play. I first considered reducing the thickness of the trigger so the bearings would seat against each other, but discovered using a spacer was easier and faster. I'm sure this isn't common knowledge and is why I offered it here. Another thing I do for stabilizing the Parma trigger is to bond the trigger bushing to the frame. In the end, the trigger sideplay is reduced to an imperceptible amount keeping the wiper flat against the resistor or board in my use. Pull hard enough on most triggers and the controller frame/chassis will flex, but I don't have that problem to deal with.

 

I've not observed a Parma trigger with oversize bearing holes, but I've dealt with less than 10 and all from Ken MacDowell-era production. I'm sure in larger quantity or different manufacturing lots this may occur. In every instance, bearings, particularly ball bearings, have fit tight, generally require pressing to some degree to fully seat, and are difficult to remove once installed. Good to know other product may be lesser quality. I'm inclined to use Difalco quality when I need something different, and I suppose I can just cut off the extra length of the trigger to suit me. In all my years of slot racing, I've also encountered my share of undersize/oversize bearings. Thankfully, my current bearing source supplies me with consistent, nominal-size bearings.

 

I've never owned or used the Slick 7 wiper buttons. I've not been impressed by the size of the thing which appears larger than the Parma button from photos I've seen. In my experience, the Parma button size is more than adequate. However, a larger diameter button with the smaller diameter resistor in Third Eye controllers seemed useful, but if the resistor and wiper are carefully aligned, the Parma-size button seems to work fine. This information about the silver is appreciated. I've had a concern about using motor brushes on the controller wiper for similar consequences - the relatively softer material and carbon building up between and shorting resistor wire turns or the spacing between board contacts.

 

I've seen slot car motor brushes used for wiper buttons, though they're really not significantly longer than the diameter of the Parma button. Something like a brush for a Dremel tool would give something larger to work with, if that were really necessary. The Parma button works, though there's less margin for error. Larger button simply gains some margin.

 

I'm sure none of what I've described here is suitable for production controllers. Different approaches must be considered for items that have to reliably assembled into a functioning unit quickly with a minimum of adjusting. I'm describing things I've done to my personal controllers to improve them for myself. The time I've spent hand fitting and getting the trigger/wiper to work well could never be expended on a production product for commercial sale. I fully realize the impracticality. My only purpose is to inform that there are things that can be done for improvement to available product if one's so inclined.

 

I'm also sure I'm somewhere well up on the nerd scale, a career engineer that even used a pocket protector full of pens and pencils in one phase of his life. Very few people would expend the time I've spent studying, experimenting, and looking for ways to make something good or adequate even better - or save a few dollars buying something else over what I already have or may be able to build for myself.

[team burrito]

I do not recommend Slick 7 silver buttons. The silver is way too soft and if you get any grit or arc on the wiper bands you will cause a groove to form in the face. Less likely with electronic controllers than the old external resistors , of course.

I believe the s7 buttons are for power & brake contacts for the Parma turbo controllers, not the wiper.

 

IMHO:  The ideal way to fashion a wiper for a Third Eye would be to use a motor brush mounted on its side and soldered to the wiper arm.  This would create a contact area that was flat and rectangular.  Done correctly, it would wipe smoothly over the barrel shape of the Third Eye resistor without "climbing up" the resistor on either end.

That's the best idea yet for an alternate wiper button.

[Jim Difalco]

Bill, you are right on most of the points in this new post. An engineer, that explains your thought approach a lot, which I like.

 

My trigger pins are threaded and tightened against the frame instead of being glued to it. Parma trigger pivot holes are not oversized but since they are just nylon the hole will widen over time causing the hole to open slightly with ball bearings. My triggers are reinforced with fiberglass and will not wear or even flex. 

 

Not sure what you mean by "I'm inclined to use Difalco quality when I need something different, and I suppose I can just cut off the extra length of the trigger to suit me." as my flat triggers are exactly the same as a Parma in the finger area. Please explain.

 

I would spend a lot of production time long ago getting oilites down to the point where the side play was acceptable. Ball bearings are more expense but way more suited for production. I load up my jig 20 triggers at a time and the process is smooth and easy.

[Jim Difalco]

i believe the s7 buttons are for power & brake contacts for the parma turbo controllers, not the wiper.

 

that's the best idea yet for an alternate wiper button.

Russ, yes you are right, they were made for brake and power contacts, but many a racer has drilled out their wiper arms and installed them. I was just cautioning against that.

 

This was mostly done in the external resistor era with full amperage going directly through the wiper button causing big arcing on the buttons.