This is why I maintain that 2mm should be used for a m3 tap.
Twist drills do not drill circular holes.
A 2.5mm hole is correct, only if the hole is accurate and circular but this is pretty hard without a mill. Even with a drill press I maintain one gets better results with 2mm hole due to the inaccuracies involved. It allows for much more error which is especially important for the novice.
2.5mm is great if you are experienced and have the proper tools. If you not then a 2mm hole will make things much much easier to get a decent result.
I like this stuff for cutting fluid
CRC 250ml CDT Oil Cutting Liquid | Bunnings Warehouse
My 2 cents.
Sure, but WD40 is still pretty good and it’s much more likely to already be in your home, compared to any cutting fluid suitable for aluminum. Why spend another $15-25 if you don’t have to?
AND, except with a blind or bottoming tap, don't back up, especially in soft material. The relief angle tries to plow the chip back where it came from, galling the new threads leaving you a snarled mess of a hole.
WD-40 is better than most bodily fluids for cutting, it's FAR from the best. Something with molybenium specially for tapping will do much better. I like to use a little acid brush to apply. Much neater and you can also use it to clean the chips from the tap.
WD-40 is better than most bodily fluids for cutting, it's FAR from the best. Something with molybenium specially for tapping will do much better. I like to use a little acid brush to apply. Much neater and you can also use it to clean the chips from the tap.
Graphite power is the most effective lubricant for tapping small holes. Remember that cutting fluids were developed and are mainly required to flush out the swarth on larger holes and milling in general. On small holes the surface tension of fluids holds the swarth in place which clogs the thread and leads to inaccuracies.
I am not a drill and tap expert but I did some research and collect some information which I think could be useful.
1) yes, keep the drilled hole "straight" (perpendicular to the metaldsurface) is important. Using a small drill press is the best (clamp the heatsink in a vise and goes slow).
2) Not everyone has a drill press, hand held power drill would work too. Best to drill with a drill cup. I tried it and it worked for me. What is a frill cup:
Search results for drill cups
Drill cups help to keep the drill bit perpendicular to the surface. Commonly use in aircraft body work.
3) I was told that the taps are designed to be "self-align", once you drilled a "proper" hole, the tap will work. As pointed out before, go slow and don't forget to clean the metal residues trapped inside the hole from time to time.
4) People found that isopropyl alcohol (IPA) works fine as a lubricant, less viscous than a lot of "real" lubricants. As mentioned earlier by someone, apply with a syringe to the hole
There are combined "drill and tap" bits, has anyone tried? Would it work?
Drillpro 6pcs m3-m10 combination drill tap bit set hss 6542 blue nano coated deburr countersink drill bits Sale - Banggood.com
Regards,
1) yes, keep the drilled hole "straight" (perpendicular to the metaldsurface) is important. Using a small drill press is the best (clamp the heatsink in a vise and goes slow).
2) Not everyone has a drill press, hand held power drill would work too. Best to drill with a drill cup. I tried it and it worked for me. What is a frill cup:
Search results for drill cups
Drill cups help to keep the drill bit perpendicular to the surface. Commonly use in aircraft body work.
3) I was told that the taps are designed to be "self-align", once you drilled a "proper" hole, the tap will work. As pointed out before, go slow and don't forget to clean the metal residues trapped inside the hole from time to time.
4) People found that isopropyl alcohol (IPA) works fine as a lubricant, less viscous than a lot of "real" lubricants. As mentioned earlier by someone, apply with a syringe to the hole
There are combined "drill and tap" bits, has anyone tried? Would it work?
Drillpro 6pcs m3-m10 combination drill tap bit set hss 6542 blue nano coated deburr countersink drill bits Sale - Banggood.com
Regards,
Twist drill bits drill fairly circular holes when the thickness of the material is at least 2-3 times the diameter of the bit.
By the way, did you know that the minor diameter of an M3 screw is just a hair under 2.3 mm? So a 2mm hole, if drilled even semi-reasonably-well, would require that an M3 tap be cutting along not just the crests but also the roots (so pretty much the entire flank of the flutes). Not only does this significantly increasing the tapping torque, it also gives you (by necessity) 100% thread engagement which doesn't always work the best for all screws. I really don't think this is the best idea.
If you are so, so concerned about the tolerance of the hole you get with a 2.5 mm twist bit, use a simple drill guide like this:
Amazon.com: Big Gator Tools MTG500NP V-Tap Guide: Automotive
Or use a brad point bit.
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If you don't need a ton of precision, they can work - there are some applications where you'd might want to bang out a bunch of tapped holes in e.g. light steel framing and they can work very quickly in an impact driver.
However, the ones you linked to look like garbage. The grinding looks terrible and I wouldn't trust a "nano" coating that has already started to wear off the edges before the photos have been taken.
10-32 Drill/Tap Bit for Stainless Steel | Greenlee
48-89-4870
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Spiral flute taps are specially made for drills and drilling machines.
I've never found any real need for them and just use standard taps in a drill.
Just be careful to set the torque very low.
Hi
Rule over the thumb is the size of the hole multiplied by 0.8
If you have soft aluminum - Not every aluminum is the same.
So you would need a drill for max 2.4mm. I would go for 2.2mm if you use a hand drill. 2.4 if you use a Standing Fixed Drill where you are sure that the hole is in a right angle to the Aluminum. As Aluminum is soft so don't use high speed on the drill. it gets the Aluminum to hot. Use some cutting fluid if you do not have this then you can take Fluid SOAP dissolved in Water not to thick and not to thin, just that it rinse easy over your finger..Keep it WET while Drilling, it gets you better nice and clean holes.
The same for the cut of the thread push the thread drill firmly in a right angle into the hole. Prior to this use either Cutting fluid or fluid dissolved Soap with water to wet the hole as well as the drill. make sure the beginning of the hole is even to the rest of the aluminum..No edges from drilling.
Rotate the thread drill two to four rounds in right direction in the hole..then rotate it backwards for a half round and forward again.this to get the chips out of way in the hole. Do this like that and you will get masterpieces of treads in your aluminum. When you screw down whatever you want to fix use a Torque Kilo Wrench where you can adjust the torque. There are Datasheets how much torque you can use for that size of bolts you are using. To much tension will kill the thread. This will prevent over tension/ torque force which will finally kill the thread after a few times using to much force.And believe me most time people tend to use too much force/tension when fitting a thread bolt. Use some silicone gel on the Screw before you turn into the thread, this will prevent corrosion between aluminum and the Iron bolt.. over a long time it may not be possible to remove the bolt because of that corrosion.. Especially when heat plays a big role on the aluminum.
Hope I could be some help
This is only for Screws thinner than 5mm..I'm drilling holes and making threads for over 50 years now..never happen that I had to trow away a piece because of the drilling the wrong sized holes..
Please take into considerations that:
1. Not everyone has good Drilling equippment
2. Not everyone knows how to sharpen a Drill that the size is what is to be expected, if the drill is dull.
3. Not everyone is using the right Drills for the right material.
4. Drilling Soft material with Fluid enlargens the holes always a few 1/100 mm of the wanted size.
5. Using too much pressure, enlargens the hole as well. Drilling dry is even worse.
6. We give answers for DIY, and we do not know how good the machinery of everyoen person is.
7. We also do not know how good the Mechanical Skills are.
8. We do not know how warm the Aluminum is, which the person intends to drill. 10C makes already a big difference.
Do you like screws which when fastened the second time, overdraws in the thread.. Good that's everyones decision.
But sure not mine..
The follow up will sound similar to that.
Hey Master Chief the Build of this piece is finished.. Shall I start to repair it?
Again, 3mm with 2.5 is ok for Iron Stainless Steel, Bronze and Brass. for week material if you are using a hand drill, 1/10th less of a milimeter is more helpfull than disasterous. You can count on that .
Please take into considerations that:
1. Not everyone has good Drilling equippment
2. Not everyone knows how to sharpen a Drill that the size is what is to be expected, if the drill is dull.
3. Not everyone is using the right Drills for the right material.
4. Drilling Soft material with Fluid enlargens the holes always a few 1/100 mm of the wanted size.
5. Using too much pressure, enlargens the hole as well. Drilling dry is even worse.
6. We give answers for DIY, and we do not know how good the machinery of everyoen person is.
7. We also do not know how good the Mechanical Skills are.
8. We do not know how warm the Aluminum is, which the person intends to drill. 10C makes already a big difference.
Do you like screws which when fastened the second time, overdraws in the thread.. Good that's everyones decision.
But sure not mine..
The follow up will sound similar to that.
Hey Master Chief the Build of this piece is finished.. Shall I start to repair it?
Again, 3mm with 2.5 is ok for Iron Stainless Steel, Bronze and Brass. for week material if you are using a hand drill, 1/10th less of a milimeter is more helpfull than disasterous. You can count on that .
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Forming taps are indeed the best way to make threads as the thread is cold-worked by the tap, and threads turn out stronger than if they were cut by a cutting tap. And there's no chips...
Well said, have 100% agreement here. In a drill press, with new sharp quality bits for 3M threads I most often drill 2.5mm, as I run out of 2.4 some time ago. While hand drilling my main size for 3M treads is 2.0 mm (sometimes 2.2) and Second pass with 2.5mm. With aluminium I almost always use two (for larger holes 3 and sometimes more) drill bits to make hole. It gets even more complicated when the hole placement needs to be within .05-.02mm precision. Then I pre-drill with centering bit in drill pres and/or keep center punching part every 0.5mm dept when hand drilling (particularly in softer alu alloys)
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