Did I buy bum taps or am I doing something wrong?

[Sayer 742]

I'm in the middle(?) of a build in the Other makes section, but today I had this happen.

And this was after I had to use vice grips to get the collet tight enough to hold the tap in the wrench in the first place. I'm trying to tap 3mm thread into 6061T6 grade aluminum bar. Should I be able to twist the tap with just hand power?

[Tamiyabigstuff 832]

Pilot hole large enough ???

Use some grease to lubricate the tap.

If the tap had twisted like that it may be poor quality - they are usually hardened steel and snap if you put too much force on them.

[Sayer 742]

Pilot hole might not be large enough. I was using a 2.38mm bit to drill the hole, hoping that wobble etc would make it close enough to 2.5mm (on account of being unable to find anything between 2.38mm and 2.75mm in my hardware store) Grease would also have been a good idea.

[KEV THE REV 2319]

Looks like carbon steel - you HSS steel taps

[SteveU30 1011]

You need to back off the tap regularly to ensure the swarf created is ejected from the hole otherwise you're just creating more work for the tap, plus regular lubrication as Tamiyabigstuff said.

[Sayer 742]

You need to back off the tap regularly to ensure the swarf created is ejected from the hole otherwise you're just creating more work for the tap, plus regular lubrication as Tamiyabigstuff said.

Thanks. The grey bit at the tip is as far as it went in, so I don't know if there was enough material to jam it yet.

[SteveU30 1011]

You should back it off a every 1 revolution at the most (I do every half) and take it out and clean it every few revolutions. Looks like you've done 4 or 5 there which is a fair bit of metal that's been 'carved' away. As mentioned already too, if your pilot hole was too small also that's going to be even more swarf. What size was the pilot hole?

[Sayer 742]

the bit was 2.38mm not sure how big the hole ended up being.

[sidewaysdave69 188]

I would of used a 2.5mm drill. And a Steve said back it off to clear the swarf out. I would also use lube, since its only alloy a thin cutting oil should be fine.

[GregM 1109]

Yes, using a HSS tap, oil lube, correct pilot hole diameter and backing off often is necessary for successful tapping.

[salvine 125]

Like mentioned above but I have yet to have a steel tap twist while going in to aluminum .

[Sayer 742]

Like mentioned above but I have yet to have a steel tap twist while going in to aluminum .

Yeah in addition to all the mistakes I made, I don't think this set was of the best quality as well (sizing already worn off taps and uncooperative wrench).

[MadInventor 3884]

I often use WD40 for cutting M3 threads into aluminium. This will be better than grease, as swarf will stick to the grease, which might prevent it from being ejected by the tap

I normally turn the tap 2 or 3 times before backing off to clear it. If cutting a thread into and open hole and it's not too deep (Like about 5mm) I just wind it straight through without backing off, as the swarf is pushed out of the bottom of the hole by the tap.

If cutting a thread into a blind hole it helps to use a spiral tap as these will eject the swarf out of the hole like a drill bit would anyway.

If the tap gets stuck or jammed, spraying WD40 down the hole and then gently rotating the tap back and forth will often free it without snapping the tap.

You should definitely be able to twist the tap with hand power. It sounds like the pilot hole is too small at 2.38mm. If you put a digital caliper across the drill bit you will probably find it is slightly small than 2.38, more like 2.28, and most drills are slightly undersize to account for a bit of wobble. I always use a 2.5mm drill for the M3 hole. If you are drilling holes with a pillar drill, you can always put the tap in the pillar drill chuck after drilling the hole and turn the chuck by hand to start off the thread, and then it always goes in square.

[Sayer 742]

I often use WD40 for cutting M3 threads into aluminium. This will be better than grease, as swarf will stick to the grease, which might prevent it from being ejected by the tap

I normally turn the tap 2 or 3 times before backing off to clear it. If cutting a thread into and open hole and it's not too deep (Like about 5mm) I just wind it straight through without backing off, as the swarf is pushed out of the bottom of the hole by the tap.

If cutting a thread into a blind hole it helps to use a spiral tap as these will eject the swarf out of the hole like a drill bit would anyway.

If the tap gets stuck or jammed, spraying WD40 down the hole and then gently rotating the tap back and forth will often free it without snapping the tap.

You should definitely be able to twist the tap with hand power. It sounds like the pilot hole is too small at 2.38mm. If you put a digital caliper across the drill bit you will probably find it is slightly small than 2.38, more like 2.28, and most drills are slightly undersize to account for a bit of wobble. I always use a 2.5mm drill for the M3 hole. If you are drilling holes with a pillar drill, you can always put the tap in the pillar drill chuck after drilling the hole and turn the chuck by hand to start off the thread, and then it always goes in square.

Hmm, well I'm going to need to get a replacement set anyway since the twisted tap is the only one in the set (and I'm not too keen on the rest of the set quality-wise) so I'll see if I can't find spiral taps. The pillar drill tip is helpful, since I was worried about that (I think you were the one who gave me the tip of bolting the rails together when drilling so the holes line up)

I thought this might be ideal since it would also supply me with the 2.5mm bit I can't find in store, but it doesn't seem to say anything about spiral taps

http://www.homedepot.com/p/Gyros-High-Speed-Steel-Metric-Tap-and-Drill-Bit-Set-18-Piece-93-17018/204626135?N=5yc1vZc22s

[SteveU30 1011]

Decent taps sets quite often come with the correct size drill bit for each tap size so look out for that!

[Wooders28 4723]

I have found the best taps to be "dormer".Not the cheapest,but good tools ain't.I find Aluminium to be one of the harder metals to tap as it grips the tap.Slow and steady,one turn in,one turn out,two in,two out etc,lots of cutting paste or wd40 etc.

[WillyChang 1814]

some of those cheapest china m3 tap can barely cut into plastic...

[Tamiya1/10 382]

some of those cheapest china m3 tap can barely cut into plastic...

this i got to see. In the end you get what you pay for. Don't expect a Holden to have the similar quality, performance...to benz s class.

[SteveU30 1011]

I have found the best taps to be "dormer".Not the cheapest,but good tools ain't.I find Aluminium to be one of the harder metals to tap as it grips the tap.Slow and steady,one turn in,one turn out,two in,two out etc,lots of cutting paste or wd40 etc.

I second Dormer, they also make excellent drill bits too, not cheap but superb quality!

[nodtec 76]

this i got to see. In the end you get what you pay for. Don't expect a Holden to have the similar quality, performance...to benz s class.

Looks like 'crap tap' to me, good ones won't bent or twist, just snap if mishandled also I use proper tapping fluid, you only need a drop, lasts for years.

Tamiya1/0, you're right, there's no way a Merc would ever be as good as a Holden.

[MadInventor 3884]

Hmm, well I'm going to need to get a replacement set anyway since the twisted tap is the only one in the set (and I'm not too keen on the rest of the set quality-wise) so I'll see if I can't find spiral taps. The pillar drill tip is helpful, since I was worried about that (I think you were the one who gave me the tip of bolting the rails together when drilling so the holes line up)

I thought this might be ideal since it would also supply me with the 2.5mm bit I can't find in store, but it doesn't seem to say anything about spiral taps

http://www.homedepot.com/p/Gyros-High-Speed-Steel-Metric-Tap-and-Drill-Bit-Set-18-Piece-93-17018/204626135?N=5yc1vZc22s

These aren't spiral taps, but the M3 tap and 2.5mm drill should do the job if you're careful with it. It's a lot cash to spend though just to get 1 drill and tap of the right size, especially if you end up snapping / blunting the drill, or damaging the tap.

This is what a spiral tap looks like:

http://uk.rs-online.com/web/p/threading-taps/2999097/

I would look for an engineering supplier in Canada that will sell drills and taps in individual sizes, the parts will cost more individually, but will be of a better quality, and you only pay for what you need. Of course, there's Ebay, but go for a good make such as dormer or Presto

[Sayer 742]

These aren't spiral taps, but the M3 tap and 2.5mm drill should do the job if you're careful with it. It's a lot cash to spend though just to get 1 drill and tap of the right size, especially if you end up snapping / blunting the drill, or damaging the tap.

This is what a spiral tap looks like:

http://uk.rs-online.com/web/p/threading-taps/2999097/

I would look for an engineering supplier in Canada that will sell drills and taps in individual sizes, the parts will cost more individually, but will be of a better quality, and you only pay for what you need. Of course, there's Ebay, but go for a good make such as dormer or Presto

Pulled the trigger before I read the suggested brands, though I ended up buying taps, wrench and bits separately. http://www.ebay.com/itm/201018791500?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648 Hopefully I don't get burned again. If so then I'll just look for the Dormer or Presto names

Not really worried about blunting the bits since despite being hesitant, I've had no problems whatsoever with the drilling part of the build.

[MadInventor 3884]

Good luck with it. let us know how you get on.

[Percymon 2184]

Perhaps I was lucky but I've no issues with the single secondary/intermediate tap I got fro ebay (complete with 2.5mm drill bit and tap 'T handle'. Admittedly I've used it mainly on plastic components but it's seem some use on alloy and steel components too.

http://www.ebay.co.uk/itm/270857397740