Group buy: 4-stud PCD redrilling tool

[biturbo228]

Hi folks,

I've been drawing up a prototype tool for redrilling PCDs on brake discs (though it should work on hubs or even wheels if you want). Should look a bit like this:



The PCDs covered (in order) are:

• 4x95.25
• 4x98
• 4x100
• 4x101.6
• 4x108
• 4x114.3
• 4x130

The holes are 12mm and it's 20mm thick, so it should guide an M12 drill acceptably. There's 60-degree chamfers on the top surface to match wheel bolts so it should locate in a similar manner to lug-centric wheels (i.e. well, but with a bit of care). For brake discs I'm planning on buying a set of M12 wheel bolts and M12 wheel nuts to bolt through the disc with chamfers on each side to locate them. It'll be made in steel to prevent wear from the sides of the drill.

As a singular piece I've had it quoted at about £150, but if there's a couple of people who want to buy in then it gets cheaper.

If there's 5 other folks who want it then it gets down to £55 each (plus onward postage). If there's 10 then it's £45 (plus onward postage). These are cost figures, I'm not trying to make a profit here.

Drop me a message if you're interested

[braaap]

I'm tempted, although I live in the land of TÜV and the need for documents for everything.

Where would You ship from or will the producer take that part?

How about a big hole in the middle and the use of spigot rings so You can also drill brake drums that have that center thing, that would be in the way without such a hole?

[biturbo228]

I'd ship from the UK. Hopefully shouldn't be too expensive, though I could get an indicative quote.

Good point on the hole in the middle! My first iteration had that, but I removed it to save a machining operation (and thus cost). However, it'd make redrilling hubs impossible as well. I'll pop it back in and see what it does to the pricing.

What sort of documents would you need? I'm just a regular bod not a company so not sure what I could get, but I'll look into it.

[biturbo228]

76mm hole poked through the middle:



£170 for a one-off
£60 if there's 5 folks
£50 if there's 10

Close enough. The hole stays as it's adds a lot more functinality.

[welshpug]

there wouldn't be any need for any papers for this, the issue you would come across is documenting the wheel post modification, i.e having it approved to be used on a different vehicle.

you could do the same operation on a mill quite easily, you'd not need to tuv paper your mill to modify a wheel

[mrbig]

Interesting concept. Might be interested. What material are you thinking? Will it be sufficiently strong to prevent the drill wondering into the tool?

[braaap]

Jul 4, 2024 12:21:39 GMT welshpug said:

there wouldn't be any need for any papers for this, the issue you would come across is documenting the wheel post modification, i.e having it approved to be used on a different vehicle.

This. Or if I change a tested part like drilling another set of holes in brake drums.

So no documents for that drill aid, but for the resulting change in other oparts.

I only mentioned this because I might step onto thin ice if I use it.

Years ago You could simply buy brake parts like discs and drums for vw bugs with different pcds. But not for other cars. It surely wouldn't do any harm to brake drums when You drill four additional holes between the existing.

But who am I to say so. An MOT (or TÜV) engineer will probably have a different view.

Of course that will not be Your problem outside Germany.

[braaap]

Jul 4, 2024 15:45:37 GMT mrbig said:

Interesting concept. Might be interested. What material are you thinking? Will it be sufficiently strong to prevent the drill wondering into the tool?

Maybe bigger holes in an aluminum tool plus four hardened drill sleeves to drill through? But that would make the price higher no doubt.

[biturbo228]

Jul 4, 2024 15:45:37 GMT mrbig said:

Interesting concept. Might be interested. What material are you thinking? Will it be sufficiently strong to prevent the drill wondering into the tool?

Jul 4, 2024 18:32:18 GMT braaap said:

Maybe bigger holes in an aluminum tool plus four hardened drill sleeves to drill through? But that would make the price higher no doubt.

Well, I've had a bit of a play around with materials in the quote.

The original is steel (S235JR seems to be most affordable). I've since found out that the quoted prices aren't inclusive of VAT which will push things up by 20%. That makes it £72 if there's 5, or £66 if there's 10.

3D printed nylon has turned out to be more affordable. £45 inclusive of VAT if there's 5 buyers, £37 for 10. It's affordable enough that I've gone for a prototype to check it works, and test whether the accuracy and surface finish is up to snuff.

I've also looked into drill sleeves, for use with an ABS or PLA 3D printed base plate. I can't find affordable drill sleeves that tell you the OD accurately, so I've looked into machined spacers. The ones from reputable places like Accu.co.uk are also expensive, but there's a fair few on eBay that certainly look acceptable. The M5 ones have an OD of 12.7mm which would still work with the base plate, and allow for a 5-and-a-bit mm drill bit to be located for a pilot hole. The question with these is how accurately do they machine the OD, ID and concentricity of the centre hole. There's a chap on an FB group who has offered the use of his 3D printer for prototyping, so I might be able to test this one out (and also get a set of those eBay stainless spacers to check accuracy). These would be £30 however many I end up ordering as the bulk purchase thing doesn't knock as much off this for some reason.

[biturbo228]

So I've been fettling with the design of the PCD adaptor tool, and found that 3D printing it was a lot more affordable so ended up ordering a prototype. I went for nylon, which reading about it isn't the best choice of material for this, but hey ho I'd already ordered it. I use Xometry for machining, mainly because it's easy to use and finding local machine shops that are in any way interested in one-off private work is difficult. Same reason I want to be able to redrill discs myself rather than giving them to a machine shop. I can't find one nearby!

This is what I ended up with:



Learnt a lot from the prototype. Firstly, I'd ordered it before the wheel nuts I'm using to attach it turned up and it turns out the taper on their seat doesn't start until ~16mm out so it only just contacts the locating portion of the tool. It still worked, but could be better.



Second issue was that the tool would need to be much taller (and made out of steel as original) to locate the drill properly. It just about worked for marking the starting point and then drilling the rest by hand, but the tip did wander a bit and required fettling and correction with a centre punch (which was a bit of a stab in the dark, though aided slightly by the ability to bolt the tool back on to check concentricity).

Pretty proud of managing to get it so that with 12mm holes it slipped over the studs of the M12 MGF hubs, though it took a lot more care, effort and luck than I'd like.



I've since discovered that transfer punches are a thing. I'd been searching in vain for ages trying to find a straight-shanked centre punch with an OD I could trust and found nothing. Was even looking at the cost of having something made up. Then, I was idly talking to my mate about this and he said 'what, like a transfer punch?'. Lo and behold I search for that and tons come up for affordable prices! There's a set on order for doing disc number 2.

So, I've drawn up a V2 of the tool. I've had to sacrifice one of the supported PCDs (101.6mm as it's the least common) to widen the chamfers. I've also upped the hole diameter to 13mm to allow for easier fitting of the bolts (and use with 1/2" hardware if needed), and switched the material to PLA which should be stiffer and cheaper. Combine that with the transfer punches and I actually think it could be good enough for general use (provided the disc is hubcentric).

That's coming out at £25+VAT for a single iteration, £20+VAT for 5, or £12.5+VAT for 10.

If anyone's interested do let me know and I might do a batch. I'd be happy to share the STEP file if anyone has a 3D printer as well.

[phil1380]

I am interested as I too have a bigger disk onto MGF/Metro hub problem to resolve.

Phil.