Juggernut

Bulk Screws vs. "RC" screws

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What's the general opinion on screws when doing rebuilds?  I ask because I can get bulk stainless screws much more reasonably priced than RC specific screws.  I'm looking at the 3x12mm tapping screws in particular that my TNX has dozens of in various states of condition:

bb7hsj2.jpg

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I use M3 stainless screws for replacements. Either hex head or button head or countersunk. Bought in bulk for much cheaper than RC screws.

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29 minutes ago, TwistedxSlayer said:

I use M3 stainless screws for replacements. Either hex head or button head or countersunk. Bought in bulk for much cheaper than RC screws.

I figure that will be the consensus.  I tend to overthink things...

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Usually, I just go to the bulk bins at the hardware store. Our local hardware stores both have a good selection of small metric hardware. That way, I can get only what I need, and I can see if there's an obvious defect in one of them and avoid it. And I don't have to wait for the postman.

The quality of the screws is important, but the quality of the tools is crucial. Don't buy cheap drivers (or use the L-wrenches than came with the kit), or even the best quality screws will give you fits.

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@Juggernut, in your original post you say you're looking at M3x12 stainless tapping screws, but the photo of the listing seems to show machine screws.  Which are you after?  Just trying to save you from a regretful purchase...

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1 hour ago, speedy_w_beans said:

@Juggernut, in your original post you say you're looking at M3x12 stainless tapping screws, but the photo of the listing seems to show machine screws.  Which are you after?  Just trying to save you from a regretful purchase...

Good catch and thanks for looking out!

The only true tapping screws in bulk that I could find had sharp points.  The ones with blunt ends were RC specific (and pricey).  I'm hoping these work but if not, I'm only out $10.

I purchased an RC screw kit for my EMaxx years ago which also had a bunch of tapping screws.  The kit came with machine screws replacing the tapping screws and they worked.

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2 hours ago, Juggernut said:

Good catch and thanks for looking out!

The only true tapping screws in bulk that I could find had sharp points.  The ones with blunt ends were RC specific (and pricey).  I'm hoping these work but if not, I'm only out $10.

I purchased an RC screw kit for my EMaxx years ago which also had a bunch of tapping screws.  The kit came with machine screws replacing the tapping screws and they worked.

The spiked ends shouldn't cause any problems as long as you're gentle which is the best way with plastic anyway. You can fid flat end ones from Chinese sellers though.

If you wanted to, some mini bolt cutters would take the end off them. 

 

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49 minutes ago, MICHAELs TopForce17 said:

I got these for my top force and had enough that I could do 45-60% on my king cab and still have some left over. 

https://rc-schrauben.de/Screw-kit-for-the-Tamiya-Top-Force

 

 

That's the kind of thing I have, just cheap Chinese ones. The only thing I would say to watch out for is the size of the screw head, it needs to be narrow like these.

I remanufacture printer toner cartridges for a living and built up a huge collection of high quality Japanese screws over time from all the scrap/reject cartridges and printers. It was a few years before I actually needed to use some on a Tamiya and lo and behold, the heads were too wide to fit in the Tamiya screw holes. Not to worry, I'm sure they will fit my Nikkos.....nope. Kyosho....mostly nope  *throws box of lovingly collected and arranged screws on the desk and sulks* I hate it when a plan doesn't come together.

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5 minutes ago, nowinaminute said:

The only thing I would say to watch out for is the size of the screw head, it needs to be narrow like these.

Yeah... I'm beginning to think that's were the problem is going to be.  I'll know tomorrow when they arrive!

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1 hour ago, Juggular said:

I got these 2 years ago, I think they were reasonably similar. (aside from the fact that you can't use flat head, and these are not JIS) 

https://www.ebay.com/itm/Practical-M3-Phillips-Round-Head-Tapping-Screws-With-Flat-End-A2-SS-100-1000pcs/191998927298?hash=item2cb40721c2:m:ms_PPEGGTO0NtldIQN0YeGw&var=491615278390

 

If these don't work, that looks my next best option.

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I got some of these for when I want to be a little "posh" too, they have pointed tips but I've honestly never had an issue because of it.

https://www.ebay.co.uk/itm/20-50-100Pcs-Grade-8-Carbon-Steel-Hex-Socket-Head-Cap-Self-tapping-Screws-M3-Z2/153465926215?ssPageName=STRK%3AMEBIDX%3AIT&var=453420596520&_trksid=p2057872.m2749.l2649

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3 minutes ago, nowinaminute said:

I got some of these for when I want to be a little "posh" too, they have pointed tips but I've honestly never had an issue because of it.

https://www.ebay.co.uk/itm/20-50-100Pcs-Grade-8-Carbon-Steel-Hex-Socket-Head-Cap-Self-tapping-Screws-M3-Z2/153465926215?ssPageName=STRK%3AMEBIDX%3AIT&var=453420596520&_trksid=p2057872.m2749.l2649

Good alternatives are coming out of the woodwork now!  I like those.

 

My only concern for the sharp tip was it popping through the plastic.

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3 minutes ago, Juggernut said:

Good alternatives are coming out of the woodwork now!  I like those.

 

My only concern for the sharp tip was it popping through the plastic.

I *think* they just taper to a point and are the same length overall rather that the sharp part being in addition to the length. I'll have to double check now!

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Stainless bolts are weak - don't use them anywhere they need to take a big load, especially a shear load, because they will snap. Get 10.9 or 12.9 alloy steel bolts ('grade 8' for imperial folk). They will rust if they get wet, but they won't break. I've filled my spare parts bins with most lengths of M3 button head hex 12.9 bolts, the cheapest from ebay, and never had an issue.

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On 6/14/2019 at 2:38 PM, Juggernut said:

I ask because I can get bulk stainless screws much more reasonably priced than RC specific screws.

Just watch what metals are used in the model and galvanic corrosion. Stainless and aluminuim don't get on, through bolts should be ok, but into a tapped hole could raise problems when you try and unscrew in a few years.

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Agree with @Wooders28 - noting Titanium coatings are wholly inert. 

So don’t ****** about testing (or abrading) a structural veneer given how the inner metal reacts with its surroundings.

Easily obtainable automotive screws (which are aviation rebadged) are cheap and tested way beyond what we need.

Not sure about hardware store bits from China ?

Probably also fine if you’ve got std racer’s insurance and ok burning whatever they’re in :) 

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I buy black oxide machine screws from McMaster-Carr in small bulk quantity. They are good quality and allow me to replace every single Phillips head screw on my builds and have plenty of spares.

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Got them and the heads are the right size and seem to hold:

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C2M5rwJ.jpg

On 6/15/2019 at 11:26 AM, Wooders28 said:

Just watch what metals are used in the model and galvanic corrosion. Stainless and aluminuim don't get on, through bolts should be ok, but into a tapped hole could raise problems when you try and unscrew in a few years.

Thanks!  I'll keep that in mind when replacing screws in the tapped aluminum holes.

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On June 15, 2019 at 8:04 AM, nbTMM said:

Stainless bolts are weak - don't use them anywhere they need to take a big load, especially a shear load, because they will snap. Get 10.9 or 12.9 alloy steel bolts ('grade 8' for imperial folk). They will rust if they get wet, but they won't break. I've filled my spare parts bins with most lengths of M3 button head hex 12.9 bolts, the cheapest from ebay, and never had an issue.

Good grief - what are you doing to that poor car that's breaking stainless bolts? In a 1:1 car, I agree; don't use them for anything structural or drivetrain-related. But for our little RC cars, I just can't see it being a problem. The loads aren't that big. I've never even broken an aluminum screw, let alone a stainless one. Bent, stripped, rounded heads, sure, but never broken.

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15 hours ago, markbt73 said:

Good grief - what are you doing to that poor car that's breaking stainless bolts? In a 1:1 car, I agree; don't use them for anything structural or drivetrain-related. But for our little RC cars, I just can't see it being a problem. The loads aren't that big. I've never even broken an aluminum screw, let alone a stainless one. Bent, stripped, rounded heads, sure, but never broken.

When the car does it's best cartwheel impression at 80kmh :). They usually bend a little before they snap. And yes, the heads getting ground off where there is a ground clearance issue - that's a problem for any type of screw though.

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2 hours ago, nbTMM said:

80kmh

Well THERE's yer problem... ;)

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