Thread: Sensitive High-speed Drill

If you want a sensitive high speed drill, you should not be looking at a mill/drill. The two things are mutually exclusive.

Also, just a drill stand for a handheld drill as per your link is not exactly a "sensitive" drilling contraption. And these handheld 20,000 rpm high speed drills usually vibrate too much for any accurate work.

I recommend you have a good look at one of these:
http://www.proxxonworld.com.au/produ...m_220_220-240v

Originally Posted by electrosteam

I need to drill some 1 mm holes in a 4 mm mild steel rod today.

The current tool of choice is a Taiwanese clone of an Emco FB2 milling machine having nice table movements, a vertical keyway to ensure good registration on height adjustments on the cylindrical column and ER16 collets.
But, maximum speed is 2000 RPM, the quill drilling movement is not exactly 'sensitive', and the collets are just a little too large.
Head drive on the column is not possible because of the backlash/friction/gravity aspects.
However, with careful work, the job will be done.

This requirement comes up occasionally and I suspect it will be more of a requirement in the future.
I am searching for a suitable economic machine with a sensitive quill movement, XY table, speeds to 20,000 RPM and standard metric small collets.

The Proxxon range is attractive, but the mills seem to be limited to 2000 RPM.
The drill is designed to accept a standard hand-held tool (which gives the 20,000 RPM) and an accessory table.
http://www.proxxonworld.com.au/produ..._head_bfb_2000

Can anyone suggest an alternative ?

Happy machining, John

cba,
Thanks for the reference, the Proxxon TBM220 drill with the suggested XY table press could be ideal.
The speed is only 8,500 RPM, perhaps that is fast enough and I do not expect to be drill smaller than 0.5 mm.
I will investigate small drill recommended operating speeds.

Point taken on the expected vibration of a general-purpose hand-held motor head.

Proxxon list an address in Tuggerah with a showroom by appointment.
That is not too far away from me, I will call them tomorrow.
Perhaps I can visit with the job in hand and ask for a demo !

John.

This eBay seller has the TBM220 for AU$270 (including postage from Germany but without the vise).:
http://www.ebay.com.au/itm/Proxxon-2...item58c3a0bbc2

Proxxon World NSW wants $322 if you pick it up from their store. Despite their picture, the price excludes the vise too. By all means, go and have a demo and ask for a discount. You can always buy it from overseas if you can wait fotr the postage.

Thanks for the reference to the German supplier - looks interesting for a number of items.
I will ponder, cogitate, consider and assess the implications of a cheaper source from a far-away place.

The Proxxon TBM220 Bench Drill comes with a set of collets of selected sizes.

Twist drills seem to be commonly available with shanks the same size as the bit.
How do I drill with a size not provided in the set ?
Do these collets cover a range of sizes like the ER range ?
Must the screwed-on chuck be used for a size not represented in the set ?
Is the Proxxon chuck likely to be good enough for very small drills ?

Some time ago at McJings in Sydney, I thought I saw solid carbide small drills with what appears to be a larger standardised shank.
When I search the net for similar items, they have proved elusive, and not even referenced in the McJings online catalog.
Can small drills be obtained with standardised shanks ?

As part of my investigations, I discovered other brands of sensitive drill presses available in the US, the Dumore brand seems to be one of the preferred.
The Dumore unit raises the table instead of dropping the quill for the stroke, and the table includes a small range XY facility.
Can anyone comment on the relative benefits of stroking the table versus stroking the quill ?

John.

Originally Posted by electrosteam

Can small drills be obtained with standardised shanks ?
John.

I think you are describing circuit board drills.

https://www.google.com.au/search?cli...MamN8QfrwYHAAw

Frank

I have a similar problem but I'm drilling into plastic. I tried a few options but just a standard dremel solved my problem. Very clean and fast drilling 4mm holes through 5mm sheet. Proxxon was my next step if I did not have any luck.

Runout is going to be an issue with a dremel at high speed. It's not that critical in plastic.

What about a pencil die grinder set up. Fix it to the headstock in the mill so you can still use the quill and x,y on the table?

Originally Posted by electrosteam

The Dumore unit raises the table instead of dropping the quill for the stroke, and the table includes a small range XY facility.
Can anyone comment on the relative benefits of stroking the table versus stroking the quill ?

When you drill with a quill and fixed table (if the counterbalance spring is correctly adjusted) the quill lever will allow some feel of resistance. If you lift the table (which could be counterbalanced - don't know), you would probably lose sensitivity because you are lifting the table and the weight of the job. I would say that a movable quill is preferable.

Michael

Their is a lot of info on the net about very small cnc milling machines. They have small and powerful dc motors that are quite adjustable in speed plus they already have the collets and tool holders for small tools. Very little runout on some of them as well.
I'm sure you could make a mount for these motors that fits in a collet holder. You could even put an extra fixing point on the depth stop collar on the quill if your worried about it rotating.

Lot of fiddling to get it up an running though.... It would be a good tool to have have on any mill.

Originally Posted by franco

I think you are describing circuit board drills.

https://www.google.com.au/search?cli...MamN8QfrwYHAAw

Frank

Circuit boards are 1 to 3mm thick, glass fibre reinforced epxy resin sheets. That is why circuit board drills are solid carbide, they would otherwise not last long drilling into the hard glass fibres. Also the geometry of circuit board drills is optimised to cut short holes (less than say 5 diameters) at very high rpm into these epxy boards.

To drill into steel and other metals, especially if the holes are deeper than just thin sheet material, HSS-Co drils are far better. HSS drills can flex somewhat before they break, whereas the solid carbide PCB (Printed Circuit Board) drills are not very good at all at flexing . PCB drills have tight spirals with very deep grooves, this makes for a smaller cross section than HSS drills designed for metals with their steeper flutes. The thicker standardadised diameter shaft is essentially there to reinforce these extremely brittle drills. I do occasionally use PCB drills on metal, but extreme care is necessary or they snap off. For this reasons they are pretty much useless for deeper holes in metal. HSS-Co microdrills are the way to go. Even with the correct drill, lots of pecking is necessary (removing the drill to clear the chips). Good quality microdrills by the way, are not parallel. They have a negative taper, meaning that the tip has the nominal diameter and the diameter reduced towards the shaft - meaning that the hole diameter is not increased because of the necessary pecking action. PCB drills are grond to be parallel, as they are only used for shallow through holes and no pecking is needed.

Sensitive bench drills that rise the table have an advantage if the workpieces are small and light. Obviously you loose sensitivity with heavier workpieces.

Many small sensitive bench drills do not have a quill. Instead one lifts the whole head with motor and belt drive up and down. This is probably slightly heavier than lifting a table. But such drills have the advantage if the workpiece is heavier or bulkier.

You can buy tiny high precision chucks for these drills. If using standard HSS and HSS-Co drills you will need such a chuck, as the shaft diameter varies by drill diameter. These chucks may clamp 0.5mm to 3mm, are about the size of a wine bottle cork cut in half, and cost as much as a genuine Albrecht 13mm chuck.

Originally Posted by Ben Dono

I have a similar problem but I'm drilling into plastic. I tried a few options but just a standard dremel solved my problem. Very clean and fast drilling 4mm holes through 5mm sheet. Proxxon was my next step if I did not have any luck. Runout is going to be an issue with a dremel at high speed. It's not that critical in plastic. What about a pencil die grinder set up. Fix it to the headstock in the mill so you can still use the quill and x,y on the table?

I have an optional tiny drill chuck for my Dremel. I haven't checked how small it will go but I am sure it would hold 0.5mm. Not sure about runout or vibration. Dean

Thanks cba, and all, for a great discussion on all the issues.

I have done some of the holes using a new Dormer 1 mm drill at 2000 RPM as previously described.
No problem at all, very impressive watching the two miniature continuous scrolls of swarf come away from the drill.

My web searches has given me confidence that the TBM220 is a worthwhile tool and that the Proxxon chuck supplied by ROHM should be up to the job.

My only concern now is ensuring sufficient head room to enable small taps to be used.
I will report back when I have acquired and tested some equipment.
John

Well, I bit the bullet and acquired a sensitive drill press.
I called Proxxon in Tuggerah and arranged a visit with a friend.
The manager is some salesman and we both left with a TBM220 each, together with the chuck, XY table and the milling vice.
According to the manager, the parts we purchased are either of European or Japanese origin.

All the bits are 'toyish', but they are nicely finished and accurate.
I think they will be a valuable addition to the workshop, as long they are not used beyond their designed applications.
I am already plotting just how I can mount the drill head onto the head of my small mill to gain the advantage of additional head space with excellent head location from the column keyway.

My only concern is the column clamp.
The head is a casting, perhaps diecast, and the housing is split and bored.
The clamp action closes the housing onto the column.
The column is accurately dia. 20 mm but the housing boring is a little too big for the clamping action.
I am open to suggestions on how to do the clamping by some other method.

Anyone considering the same action, check the catalog as the small mill/drill we saw with speed to 6000 via a controller looked like a superior bit of kit, but with some increase in price.
As we both already had a small mill, we elected to go with the drill only.
Note also to allow some time to get a good sales job, and there is a very nice lunchroom nearby.
Hanging on the wall as you enter is a Hot-wire cutting machine with CNC control, a local development.
Apparently being on the wall means you can close the path without the part falling out of the blank.

In the photos below the tool is holding a 1 mm drill and there is 65 mm drill tip to the top of the vice.
The vice itself is 25 mm high.

The first test job was only 1.6 aluminium, but it went well.

Proxxon TBM220 2 Compr.JPGProxxon TBM220 1 Compr.JPG

Looks good for the future,
John

Originally Posted by electrosteam

.................
My only concern is the column clamp.
The head is a casting, perhaps diecast, and the housing is split and bored.
The clamp action closes the housing onto the column.
The column is accurately dia. 20 mm but the housing boring is a little too big for the clamping action.
I am open to suggestions on how to do the clamping by some other method..................
John

Hi John,

From what I can see on pictures, there are two clamping collars to lock the head to the column:
tbm220_withoutcover.jpg
The clamping collar bore must of course be a close fit to the column. Are both top and bottom clamp really bored oversize? If so, that would be something for a warranty claim.... or at least some extra discount.
How much are the bores oversize? Or is the problem possibly some paint overspray inside the clamp bore edges, or maybe some slippery transport grease on the column?

cba,
Yes you are correct, two clamps.
The upper clamp bore is 20.07, the bottom 20.1 - hardly cause for complaint, but different to the precision fits we are used to on our machinery.
The amount of torque necessary on the short tommy bars seems excessive.
I am sure my unit is simply near the limit of the production range.
John.