Enlarging Holes in Thin Aluminium

[Dr_GMJNParticipant @dr_gmjn]

All, The final thing I need to do on my 10V is enlarge the pilot holes on the aluminium cylinder cladding, to suit the drain cocks and exhaust stub.

I ordered a 4mm -12 mm step drill (1 mm increments) becasue I need 6 mm and 7 mm holes. I could only find a 1 mm increment step drill for a resonable price from Cutwel. They have now told me they cant get it until mid November, so I cancelled the order.

There must be an alternative way of enlarging these pilot holes. One hole is on a flat part of the cladding, the other two are on the curved part. I'm worried that sequentially drilling the pilots will cause grabbing and ruin the job.

Any suggestions?

Abrasive paper wrapped around a tapered stub and spun in a Dremel?

Thanks.

[Dr_GMJNParticipant @dr_gmjn]

[John HinkleyParticipant @johnhinkley26699]

I don't know where you've been searching but I've looked on Arc's site and found one there and there's more than you can shake a stick at on another site. For around a fiver, if you want. Can't vouch for the quality, mind, nor give you a link, sorry.

John

[Clive Brown 1Participant @clivebrown1]

A round needle file?

[Bo’sunParticipant @bosun58570]

There are tapered reamers specifically for enlarging holes in electrical panels. You could try someone like RS Components.

[Dr_GMJNParticipant @dr_gmjn]

Posted by John Hinkley on 13/10/2020 11:57:13:

I don't know where you've been searching but I've looked on Arc's site and found one there and there's more than you can shake a stick at on another site. For around a fiver, if you want. Can't vouch for the quality, mind, nor give you a link, sorry.

John

It's a shame you can't give a link becasue I can't find any step drills on Arc to the specification I mentioned.

[Oily RagParticipant @oilyrag]

Bought a set of 3 step drills (3mm to 22mm ) from Lidl recently for £3.99 – even if they are carbon steel, whilst they claim to be HSS, as is often claimed by Chinese tool manufacturers (I think some of them think HSS means it's High Sulphur Steel! ) they will certainly cut aluminium – even L72 grade.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Clive Brown 1 on 13/10/2020 11:58:39:

A round needle file?

Yes, I guess so, but I'd like a very clean-edged hole, concentric with the pilot, and I'm not that good at filing.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Oily Rag on 13/10/2020 12:04:56:

Bought a set of 3 step drills (3mm to 22mm ) from Lidl recently for £3.99 – even if they are carbon steel, whilst they claim to be HSS, as is often claimed by Chinese tool manufacturers (I think some of them think HSS means it's High Sulphur Steel! ) they will certainly cut aluminium – even L72 grade.

1 mm increments?

[Stuart Smith 5Participant @stuartsmith5]

You could use a cone drill bit.

This set is from Screwfix:

**LINK**

Seems to work ok on thin sheet.

Stuart

[Dr_GMJNParticipant @dr_gmjn]

Posted by Bo'sun on 13/10/2020 12:03:23:

There are tapered reamers specifically for enlarging holes in electrical panels. You could try someone like RS Components.

That sounds like an option – are they likely to grab the metal, or do you just turn them slowly by hand?

Thanks

[Perko7Participant @perko7]

You don't say how thin the aluminium is, but would a hole punch be a suitable method? I've made some in various sizes to punch bolt/stud holes in gasket material and found they work just fine on shim brass so maybe they would work on thin aluminium sheet too?

[Dr_GMJNParticipant @dr_gmjn]

Posted by Stuart Smith 5 on 13/10/2020 12:05:57:

You could use a cone drill bit.

This set is from Screwfix:

**LINK**

Seems to work ok on thin sheet.

Stuart

Thanks Stuart. That's an option, although I suppose like the reamer, it will leave a tapered hole.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Perko7 on 13/10/2020 12:09:35:

You don't say how thin the aluminium is, but would a hole punch be a suitable method? I've made some in various sizes to punch bolt/stud holes in gasket material and found they work just fine on shim brass so maybe they would work on thin aluminium sheet too?

It's a mm or two, so too thick for that really. Plus I'd have trouble getting the punch concentric with the pilot.

[Nick HughesParticipant @nickhughes97026]

Comwell: 4mm – 12mm 9 Step- 4-12mm 9 Step

[not done it yetParticipant @notdoneityet]

How thick is this cladding? I would sandwich it, for support, and cut with an end mill if the material is flat. If really thin, a hole punch would suffice – the way I cut holes in gasket material if unsuitable for cutting with a ball bearing or small ball-pein hammer.

edit to say I’ve since seen the last couple of posts🙂

Edited By not done it yet on 13/10/2020 12:18:59

[Oily RagParticipant @oilyrag]

Posted by Oily Rag on 13/10/2020 12:04:56:

Bought a set of 3 step drills (3mm to 22mm ) from Lidl recently for £3.99 – even if they are carbon steel, whilst they claim to be HSS, as is often claimed by Chinese tool manufacturers (I think some of them think HSS means it's High Sulphur Steel! ) they will certainly cut aluminium – even L72 grade.

1 mm increments?

3mm to 12mm in 1mm increments then 14, 15, 16, 18, 20 & 22mm

[Dr_GMJNParticipant @dr_gmjn]

Posted by not done it yet on 13/10/2020 12:17:26:

How thick is this cladding? I would sandwich it, for support, and cut with an end mill if the material is flat. If really thin, a hole punch would suffice – the way I cut holes in gasket material if unsuitable for cutting with a ball bearing or small ball-pein hammer.

edit to say I’ve since seen the last couple of posts🙂

Edited By not done it yet on 13/10/2020 12:18:59

Thanks, but two of the holes are on a curved surface.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Oily Rag on 13/10/2020 12:17:30:

Posted by Oily Rag on 13/10/2020 12:04:56:

Bought a set of 3 step drills (3mm to 22mm ) from Lidl recently for £3.99 – even if they are carbon steel, whilst they claim to be HSS, as is often claimed by Chinese tool manufacturers (I think some of them think HSS means it's High Sulphur Steel! ) they will certainly cut aluminium – even L72 grade.

1 mm increments?

3mm to 12mm in 1mm increments then 14, 15, 16, 18, 20 & 22mm

That would have been fine! Can't see it available now though.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Nick Hughes on 13/10/2020 12:16:21:

Comwell: 4mm – 12mm 9 Step- 4-12mm 9 Step

Thanks – that looks like a good candidate. I'll give them a call – they're only 20 minutes away.

[JasonBModerator @jasonb]

You can also just plunge cut with a milling cutter, 3-flute would be mu choice but 2 or 4 will be OK as you already have a pilot hole

[Dr_GMJNParticipant @dr_gmjn]

Posted by JasonB on 13/10/2020 12:58:24:

You can also just plunge cut with a milling cutter, 3-flute would be mu choice but 2 or 4 will be OK as you already have a pilot hole

The very thought terrifies me with the current gas-strut setup I've got on the SX2P. I started another thread on the subject, but basically, the strut I fitted is slightly over-compensating for head weight, which is being pushed up by default. This seems to be making cutter grabbing almost inevitable when feeding down, since there's nothing but a bit of friction and minimal residual gas pressure preventing the head from moving down. I have effectively no fine control of the head in a -z direction.

I just ordered a set of cheese-based step drills from Amazon. I really wanted a decent one that will last, but these should do the job at least once. I just want to get the engine finished.

Cheers.

[John HinkleyParticipant @johnhinkley26699]

When I wrote I couldn't post a link, I could have, but it would have been moderated out under the CoC rules. I'll PM you.

John

 

Edited By John Hinkley on 13/10/2020 13:49:06

[mechman48Participant @mechman48]

I've lost track of what's going on … can't post links under CoC rules… ' what's CoC' ?… any thing to do with My Time Media ? what links are /not allowed … eBay et al ? … Help!

George.

[Dr_GMJNParticipant @dr_gmjn]

Posted by John Hinkley on 13/10/2020 13:48:43:

When I wrote I couldn't post a link, I could have, but it would have been moderated out under the CoC rules. I'll PM you.

John

Edited By John Hinkley on 13/10/2020 13:49:06

Thanks John for the PM – those are exactly the ones I just ordered from Amazon. As I mentioned, I really wanted some better quality ones (some of the customer reviews are pretty dire regarding wear), but they'll do for now.

I was wondering where the Arc ones you mentioned were on their website, I couldn't see one with 1 mm increments.

Cheers.

[Author]

Posts