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Anyone lately go full machine screws and ditch Tamiya self tapping?

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I did read some of the previous threads about screws and all but curious if anyone has fully committed to machine screws (hex) vs Tamiya's provided self tapping screws? Any regrets? 

Aside from that I'm also not much of a fan of Phillips screw drives for use in RC cars. In my last few Kyosho builds I found it more practical, faster, and precise using hex machine screws. I'm about to bite the bullet and get bulk metric hex machine screws so just wanted to see what's up with others on screws. Thanks.

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I lean towards tapping for m3 where I can and using button or capheads. Since a lot of my stuff is printed or restoration where actress have already been used it tends to be a mixture. 

I think it matters more the higher end you go

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You can get on better with Tamiya screws if you use a correct JIS driver.

But I agree, I prefer hex hed screws. I have tapping screws with hex heads now which I use to retrofit models that have already had tapping screws in them rather than try and switch to machine screws and chew the screw holes up.

I've literally just started using machine screws for new builds. The only unnerving thing is how tight they are compared to tappers, it feels like failures waiting to happen when the plastic gets old and brittle!

I've been alleviating the issue but putting a dab of grease on the screw before inserting it. This reduces the friction a lot. Some people also heat the screw up with a soldering iron to make the plastic soft and more malleable. Seems like it would be a bit time consuming though.

Aside from the hex heads making life easier (the stock screws really do benefit from a JIS driver but even so, Hex is still better for other reasons such as when you have to thread the end of the driver through various parts of a model without the screw falling off etc) the other advantage of machine screws is that they hold stronger and give a much more positive feedback of when they are fully "in". You're much less likely to strip them.

Either way, if you enjoy hex heads, I can recommend getting tapping screws with hex heads to retrofit older models.

I usually get screws by the 100 from China. They work out really cheap and if you get the half decent A2 or 12.9 steel ones, they are usually the exact same thing UK hardware stores sell anyway.

If I'm in a pinch though, Kayfast have always given me exceptional service via ebay and if you buy in larger quantities, the likes of UKstainkess and a few other UK sellers work out cheap too, often a couple of £ per 100. It might even be cheaper to buy UK for the common stuff now that Brexit has happened. The more niche stuff will probably still be cheaper from China though.

Either from China or UK though, you will find they are a fraction of the cost of "model" hardware. When I first got back into RC in 2016 I was quite naive and always went with the "proper" branded stuff to be safe but over time, I realised that it's mostly just standardised hardware that you can easily buy for 1/10 of the price without sacrificing quality. (You can go cheaper still but who wants screws snapping off in their rc model after a crash?)

Same applies for nuts be they plain, nyloc, flanged, serrated etc. You'll pay a ridiculous mark up for a bag of "RC" nuts vs generic stuff that's functionally identical.

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After using hex screws on my trail rig, I would like to continue using them.

I pulled out an M03 chassis out of storage the other day and found I'd assembled it with hex kit. I can't remember where I got it from now - could have been RCMart or Banzai but I think it was a chassis specific box set. I do remember them being tight and should have used the grease trick.

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All of my Tamiya builds get machine screws. When I'm building, I put a little dab of grease on my mat and put a little on each screw to reduce friction. Sometimes, I'll tap reinforced plastics, and I usually tap 3D parts, but it isn't always necessary. Just replacing the self-tapping screws really improves the quality of the entry level cars.

Also, I hate Phillips heads. 

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I used to hate the Tamiya screws until, as stated, I actually bought the correct screwdriver. Cheaper to buy a JIS screwdriver than swap all your screws. 

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JIS tamiya screws are a pleasure, hex less so, I hope tamiya never change this philosophy!

Also I'll never use a power driver, manual driver only.....there's no rush to finish a build!

Edited by taffer
Extra bit
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I'll use button head hex screws wherever I can ( apart from king pins etc) I find them so much easier to work with especially with a magnetised bit in a powered screwdriver. Although I never rely on torque settings and do the last bit by hand.

Good quality tools and screws are the key, and I generally buy my fixings from Modelfixings.co.uk.

 

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I get stainless torx head self-tapping through McMaster-Carr in the US. I only do machine screws where I know I can go through the material and use a nut on the end.

As to why torx over JIS - familial tremor runs in the family. It hasn't hit me yet, but I already find JIS/Philips frustrating, so a screwhead that holds the driver is preferred.

Same reason for torx over regular hex - better mating between the screw and driver, and I find I'm much less likely to use the wrong key (what a nightmare metric/imperial are) and round them out.

Cheers.

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I use Tamiya self tapping screws as intended. Tamiya molds many of their products from un-reinforced ABS and PC plastic (though they also use PA regularly depending on the part). I imagine the minor diameter between a self tapping screw and a machine screw  is different despite having roughly the same major diameter. When Tamiya molds a hole it is likely intended for a specific fastener type which is one of the reasons why machine screws feel rather tight being threaded into hole originally molded for self tappers. 

1 hour ago, nowinaminute said:

Some people also hear the screw up with a soldering iron to make the plastic soft and more malleable. Seems like it would be a bit time consuming though.

I'm guilty of this, especially for new builds I intend to run. It is time consuming but reduces the amount of stress screws create on a part when being driven in. In some cases, parts that fail down the road were actually damaged at the initial point of screw insertion. Impacts from running simply caused the initial fractures to spread. A fellow with a great deal of knowledge keeping Tamiya cars together on a race track clued me into this. ABS gains much of its strength through mass. Screws driven into intricate pieces with minimum wall thickness are common failure points.

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Thanks for the feedback. Sorry was generalizing the + screw drives. I actually only use JIS on Tamiya or JIS screw drives. Use a mix of Japanese JIS drivers for cars and motorcycles. But having done both and having an electric drive I just find hex quicker (also less prone to cam-outs— regardless if I use a JIS driver on + screws). But aside from that the self tapping screws direction is what I want to replace with machine screws—probably the bigger interest. It’s just on higher end or race kits I’ve encountered, there rarely are self tapping screws. I’m building a Super Astute and then Egress and I wanted to skip self tapping when and where I can because I sort of feel those cars are on a higher level than say a Hornet or Hotshot and needs that special attention. I think that’s also my dilemma. Made me think that probably the plastics on some lower end Tamiyas are just more brittle/cheaper. 

@isomer1 interesting direction on Torx. I can see that. Also getting screws from McMaster. How do you personally determine /decide what Tamiya plastic can use machine screws? Any tips?

@Saito2 makes sense on why they provide self tapping. In addition, I remember reading articles back in the day about why Tamiya does that—makes it easier for entry level enthusiasts to build cars. 

While were at it, is there anyone here who knows what the flat head countersink screw angle is for Tamiya countersunk holes? Is it 90 degrees? McMaster offers 82, 90, and 100. There are many choices with 82 and 90 and both metric. I’m assuming it’s 90 because 82 seems too tall. And 100 isn’t metric at all with fewer lengths. Thanks again.

 

 

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Getting a hex out when it all goes wrong in a lot harder. Machine screws tend to be a lot finer, shallower, thread so not sure they will work with all the Tamiya plastics 

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I wouldn't buy a used tamiya if it had anything but tamiya JIS, it would kill the value for me....

Rather than heat screws etc, I've built my tamiyas for at least five years slowly, doing only one or two turns of the driver, rest then continue..... rapidly screwing in non stop, I used to be able to feel the heat build up in the screw head......

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Those that use machine screws, do you tap the holes first?  Or use the screw to make the threads?  I considered using machine screws because I have easy access to stainless screws at work.  I figured using a form tap might work wonders.

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I swap out tapping screws for SS or aluminum M3 screws in almost all of my RC’s. I hate rusty screw heads more that I dislike using Phillips heads.

In plastic, I’ll start with a 2.5mm drive socket cap screw to cut the first round of threads. Usually it gets warm enough that I believe it will soften the plastic such that it doesn’t split.  I’ll let it cool before removing it.


For final assembly I’ll switch to a button-head, first turning the screw backwards to feel it “click” into the thread I started with the socket cap screw.  This assures that holes don’t get stripped. 

If the substrate is unusually hard, such as the reinforced parts, I’ll use a M3 tap to about 1/2 depth to start cutting threads but still have enough interference for the screw to get a good bite. 

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3 minutes ago, kwkenuf said:

Those that use machine screws, do you tap the holes first?  Or use the screw to make the threads?  I considered using machine screws because I have easy access to stainless screws at work.  I figured using a form tap might work wonders.

I've just been using grease on a screw to be honest. You have two choices with taps as far as I know. The kind that removes material and the kind that displaces it. The former type supposedly defeats the object a bit because it results in smaller threads and the latter type doesn't really give a functional advantage over just using a screw.

I would expect the soldering iron method would probably be the safest way to get a screw into "lesser" plastic without damage but I haven't done it much so far. Worth noting that I've had plastic split even on brand new stuff before now though and even when machine hardware was supplied by Tamiya. M-05 is one notable one I can think of, I'm sure something cracked in the vicinity of the steering crank.

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I hate the + head hardware (yes I've got the right JIS bit), but always prefer to replace with Hex head where possible.  I don't really like the self tapping screws, I feel they are probably just used because they give secure and reliable results when hastily screwed into plastic. 

I find that if the m3 screws thread themselves ok (ie. not too tight), then I just work them back and forth a few times to cut the thread and relieve stress in the material.  If they seem really tight to thread, then I'll tap the hole with a tapered tap so the screws can kinda finish cutting the thread giving a nice snug fit, the thing to avoid is using the full sized tap for tapping a threaded hole (with a bottom), in metal this is fine as it has no real flex, where as in plastic the tapered tap gives a smaller than m3 hole, allowing the hole/threads to flex and shape slightly as the screw goes in, to give a nice fit.  If you use the full sized tap in plastic the hole/threads will still flex but end up giving you a slightly loose fitting screw, (which is bad).

I've got an 2011 Avante to do soon and it's such a shame it comes with the JIS screws (same applies to the Egress I presume), has anyone installed the Titanium screw kit into an Avante, and/or knows whether they include replacement self tappers or just machine screws for all the hardware?  I'm a bit more apprehensive about swapping the self tappers on the Avante, because parts are obviously more expensive/rare compared to Frogs, Hoppers and the Hotshot family, if there ever were a problem with the machine screw hardware.

I've done a rere Kyosho Optima and there were a few self tappers on that kit, but as they had nice hex fitting heads I didn't feel as much of a need to replace them as I will with the Avante + fitting ones.

Having said all that I am by no means an expert and would love to hear what the highly experienced RC builders do.

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I've used QUALITY Hex Head Screws wherever I can. Even on my Axials, which come with Hex Screws.... They're so soft, that removal often ends up in STRIPPED Heads!! A real PITA. 

Also, if you stick with 2.5mm Hex Heads instead of 2.0 or 1.5mm Heads, your chances of damaged Fittings is drastically reduced.

I agree that Torx Screws are even better, but in some cases, they're harder to find in bulk, and more expensive.

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Can’t stand hex screws 

I do prefer machine screws though but I just use what’s in the box

some recent builds that use machine screws are way better though and I do have a cheapo box of hex machine screws from Banggood for standbys

JJ

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Are we talking about speed / convenience or quality here ?

Two very diff things - that, we all know, rarely align 🙄

It’s true self tappers - and esp titanium - cam out ... some first time, most with use 

It’s also true their diameter and edge tip angles - which form the bite - are diff than equivalent hex or machined 

Broadly, they bite wider (and a little upward) vs  hex - so the latter in the same place are prone to stripping under load - which is pretty much @Saito2s point 

The cam issue is fixed with JIS drivers 

And deforming plastic under load is fixed either with a thread forming tap or heat / vaseline plus a carefully weighted hand 

Not sure why anyone would then opt for hex if it’s not a convenient shelfer ?

Which, for me, would still have the wrong screws 😂

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I always change all the stock Tamiya screws to hex-machined screws. Steel for the under chassis and aluminium for the screws on top and internals.

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Only Tamiya I have with hex hardware is my M-03, but I bought all the appropriate screws from DuBro, the Jimny, Clod, and Lunchbox were and the GF-01 will be built with stock hardware. Most of my other R/Cs are either hex from the factory or I have converted them over, think my Wheely King that was stretched and has the Proline Clod sized tires may be partially factory Phillips, but I just can’t remember any more.

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That's it, going to go purchase bulk stainless machined screws/hex from McMaster. Thanks all.

By the way, I just realized the old Scorpion from the '80s uses + drive and then the re-re is hex machined. Also, wanted to mention that aside from some kits I have with hex, it was Tamiya driver Satoshi Maezumi's Super Astute that made me also think about going hex/machine with my SA build—and the TRF buggies are mostly hex/machined anyway. Wish the Egress came with hex screws.

 

3 hours ago, SuperChamp82 said:

Are we talking about speed / convenience or quality here ?

Two very diff things - that, we all know, rarely align 🙄

What?! :)  fast food, VIP passes, bullet trains, traveling by plane vs boat, online purchasing, internet, ride hailing services, city bikes, power tools, quickies and so on! hehe.

 

 

sa.jpg

sa2.jpg

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I only convert + to hex if it's already an M3 machine screw, otherwise I leave the self tappers alone. I prefer the heartier bite of the coarser thread, and if it starts to get a little loose, just add some super glue to the threads before putting the screw back in.

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