Hit It With A Hammer!?! REALLY?

[HO RacePro]

One of the best 1/32nd builders/tuners/racers I know let slip with a speed secret recently -- that he will tap his can motors with a hammer. He claims it is usually good for adding a couple hundred peak RPM's. He confesses he doesn't know why it should work, but he insists it does. He has a theory that it helps settle the magnets closer to the armature.

Now I am so impressed by this guy's ability to produce race-winning cars that if he suggested I put my slotcar in a burlap bag, go out onto my front lawn, swing it over my head and scream like a chicken -- I'd at least consider it. So I just bought a small brass-head hammer specifically for -- yes -- rapping on my slot motors.

I happen to have a DIY dynamometer for can-style slot motors. I ginned it up some time ago. It does work, and it allows me to vary the load and the voltage while monitoring the current draw of a motor. I haven't used it much because in early testing it seemed to show a motor's performance was more dependent on its amount of break-in than anything else. At least that is the impression I got. I really need to spend more time on it.

But at least I have a way to check the peak RPM's of motors pre- and post- hammering.

Things at home have been hectic of late. Time in my basement mad-scientist digs has been scarce. But I intend to investigate this some when things calm down a bit.

In the meantime, can anybody confirm or debunk this technique? Better yet, explain why it might work?

[Pappy]

Just remember, if it doesn't work, try a bigger hammer .

[JCIS4ME]

A BFH !!!!!!

[chrisguyw]

Moving the magnets closer to the armature will not increase RPM, but, will increase torque,....that said, for the very very marginal decrease in air gap (Stack face to magnet face), by tapping with a hammer, the results will be infinitesimal at best,....and there are some very real issues that result from hammering/crushing, and therefore distorting a can. Additionally the magnets in our toy motors are securely held in by either "U" clips or indents in the can itself, and any movement of the magnet face closer to the stack (from tapping) is wishful thinking,.......and again reducing the air gap does not increase RPM.

It was fairly common a few years back for the European IMCA racers to slightly crush the sides of the cans in the Plafit "Fox" motors that were mandated, to try to marginally increase the torque . Bringing a magnet closer to the armature (reducing the air gap) will only increase torque, and unfortunately will have a negative effect on RPM. Unfortunately, crushing the can tended to distort the alignment of the motor bushings and most folks ended up with a poorer performing motor. It can also distort the mounting face of the can, which presents issues when mounting the motor in the chassis. We had a problem with this at the IMCA Worlds held in Toronto in 2009, as several inexperienced racers tried crushing the can, and ended up ruining motors.

The manufacturers (Koford, ProSlot, Camen, Mura etc. ), of high end slot motors, and , most of the serious racers of high end cars have been playing with magnet gauss, air gap, stack diameter, can design , wire dia. and number of wire turns since the mid 60's., and can crushing was never a solution. One of those manufacturers ( Stuart Koford) became so respected/renowned for his slot motor knowledge, design and engineering, that he was employed by NASA to develop electric motors (particularly brushless motors) for the space program...........Stuart does not "tap" motor cans...

A very long standing and well accepted principle of electric motors.......increasing the air gap increases RPM, but lowers torque,.....reducing the air gap, increases torque, but, reduces RPM.

Cheers
Chris Walker

[Pappy]

Back in the 60's we would put a piece of masking tape on the back side of the magnets to reduce the gap.

[LAMing]

What sometimes helps is to simply hold the running motor between your fingers and thumb, and slap it onto a hard surfaced table. (Use some discretion here. Don't pile drive it, simply slap it lightly onto the table top.)

You will hear either no change, or a slight increase in RPM. (What you don't want to hear is a slight slowing!) What this can do is help the front/rear bearings to seat so they are more concentric with each other as well as being more parallel with the shaft.

It's a trick that I've used with model RR motors as well as slot car motors. More often than not, slight gains can be had with a new, stock, motor.

[Aptosc6]

This sounds like a feeble attempt to improve alignment between the bearing surfaces. On 1/24th scale motors one or both bushing can pivot to self align. When the bushing are in alignment the armature shaft will spin more freely and you use less energy as well. These motors also get "blue printing" to make sure the motor is optimized.
In theory, you could loosen up everything on the motor can, spin it up, and move things around until you hear the frequency increase. Lock it down and listen to ensure nothing moved.

[4380r]

One of the best 1/32nd builders/tuners/racers I know let slip with a speed secret recently -- that he will tap his can motors with a hammer. He claims it is usually good for adding a couple hundred peak RPM's. He confesses he doesn't know why it should work, but he insists it does. He has a theory that it helps settle the magnets closer to the armature.

Now I am so impressed by this guy's ability to produce race-winning cars that if he suggested I put my slotcar in a burlap bag, go out onto my front lawn, swing it over my head and scream like a chicken -- I'd at least consider it. So I just bought a small brass-head hammer specifically for -- yes -- rapping on my slot motors.

I happen to have a DIY dynamometer for can-style slot motors. I ginned it up some time ago. It does work, and it allows me to vary the load and the voltage while monitoring the current draw of a motor. I haven't used it much because in early testing it seemed to show a motor's performance was more dependent on its amount of break-in than anything else. At least that is the impression I got. I really need to spend more time on it.

But at least I have a way to check the peak RPM's of motors pre- and post- hammering.

Things at home have been hectic of late. Time in my basement mad-scientist digs has been scarce. But I intend to investigate this some when things calm down a bit.

In the meantime, can anybody confirm or debunk this technique? Better yet, explain why it might work?

Maybe he’s faster because he tricks his competitors into hitting their motors with a hammer.

[chrisguyw]

On 1/24th scale motors one or both bushing can pivot to self align.
.

Just curious to know which 1/24 motors have a pivoting endbell and or can bushing...........I have been racing 1/24 cars for quite some time and have never seen one.

Cheers
Chris Walker

[RichD]

When I was tuning motors for 1/24th scale commercial raceway cars I always removed the armature and checked the alignment of the bearings with a drill blank. I have observed that the armatures of FC130 motors are never properly aligned with the magnets and that the motors are likely to run better if the magnets were re-positioned. Since the rules forbid opening up the motors I have not done that.

[Pappy]

Just curious to know which 1/24 motors have a pivoting endbell and or can bushing...........I have been racing 1/24 cars for quite some time and have never seen one.

Cheers
Chris Walker

I think that's the way the Parma #499 Super 16D worked.

https://www.worthpoint.com/worthopedia/24-parma-rotor-499-adjustable-timing-309122565

[Aptosc6]

It seems to me it was Parma on their high end set ups. If you bought a motor "set-up" kit you often got a bag of parts with slightly over sized hole on the can side. You use a slug with the size and shape of the arm set with a drill blank. In the process of blue printing this stuff you assemble every thing, clamp together and solder the can bushing. After, you test with a drill blank to check friction. Repeat until you are happy with the results.

Did I mention that ceramic magnets chip and crack easily so hitting them would be disastrous.

[chrisguyw]

I think that's the way the Parma #499 Super 16D worked.

https://www.worthpoint.com/worthoped...ming-309122565

Hi Pappy, The Parma #499 rotor motor, had adjustable timing,.............they did not have pivoting can or endbell bushings.

Cheers
Chris Walker

[chrisguyw]

It seems to me it was Parma on their high end set ups. If you bought a motor "set-up" kit you often got a bag of parts with slightly over sized hole on the can side. You use a slug with the size and shape of the arm set with a drill blank. In the process of blue printing this stuff you assemble every thing, clamp together and solder the can bushing. After, you test with a drill blank to check friction. Repeat until you are happy with the results.

Did I mention that ceramic magnets chip and crack easily so hitting them would be disastrous.

Building and blueprinting is another thing altogether, I have done many, with most if not all can bushings being soldered in.............the pivoting can and or endbell bushings you referred to are another thing altogether, and I have never seen any since Mabuchi launched the first "can" motor (the FT16) in 1963.

Cheers
Chris Walker

[Bill from NH]

If the bearings/bushings are just pressed in, a light hammer tap will fully seat them giving a few additional thousands of armature side play. If the bearings/bushings are soldered or glued in, you can hammer them all day, but they aren't going to move.

[JCIS4ME]

Lots of good suggestions! The tapping with a hammer jarred the components of the motor just loosened up the internal workings of the motor.When manufactured the bushings just get pressed in so they may not be perfectly straight, so by hitting it with a hammer it moved it more in line the the armature shaft thus spinning faster. Like Rich D and others have mentioned "Blueprinting" 1/24 scale motors being that most club races DO NOT allow taking the motor apart, so "Blueprinting" would not be allowed.But by tapping on the motor will loosen up the inner workings of the can motor, a can bushing may be off just a bit or the end bell just a little crooked . . . There isnt really a lot you can do with a "Sealed" motor but manipulating the motor
wiggle armerature shaft grabbing the can bushing with pliers to reset the bushing, CAN make the RPM'S faster. (by hitting it with a hammer not suggested)!
Side note I ran a Slot car shop way back in the late 80's and we had a complete miniature machine shop. Tried the "cut the can" to make the rpms higher ( barely worked and alot of wasted cans). using pliers to squeeze the can to make the magnets be closer to the "arm" which BTW created more torque. We machined commutator on the arms and got a higher RPM reading. (timing) Yes you can time a motor to be faster or have more torque but alas not allowed in the "Rules" But back to our smaller home motors just fiddle with the bushings making sure there is no binding, after a while you will feel the difference in how the arm moves and spins (side note) leave the pinion on to help get the feel of movement. After a while you can and will get the feel of it!
My buck 2.98's worth!
Marty
T.R.Raceway
Toms River NJ