Questions regarding drilling small holes, and runout.

[Gavin1024]

Hello! I have a Hamilton sensitive drill press (model A-M) that uses a JT1 tapered (<-- I think) jacobs chuck, and maxes out around 7k rpm. The runout from the shank of a 3mm bit is 0.08 - 0.1mm. The runout of the spindle just above the chuck is 0.01mm. As I said before, I'm not positive of the taper, but I think it is a JT1. I have not removed the chuck to check the taper runout yet.
I found a JT1 -> ER11 collet chuck that states 0.008mm TIR, and I figured pairing that with an ER11 rego-fix collet, worst case, would put me at .03 - .04mm? At least cutting the current in half.
Going further than that, I have seen videos of people marking and filing the high spots on their collets, which I am open to trying. I do have varying grades of lapping paper both cloth and firm from 1um up to 40um.

Aside from that above, I feel I should also say, there does seem to be quiiite a bit of vibration when running full speed, which I'm not sure how to go about reducing. or know how much effect the accuracy. Though, I have not taken apart the spindle or anything. Only replaced idler wheels / bearings. Would this vibration when running at 7k make my runout much worse than when turning slowly by hand? or is it still negligible?

And then I was thinking, how much does this runout actually effect me in my operations? For example this tapping set I have says if I want to tap for a 0.5mm threaded hole, I need to drill a 0.4mm hole. If the difference here is only 0.1mm, does my 0.1mm+ runout effect that any? Or is this a case where 0.1mm runout doesn't mean the hole size varies by 0.1mm, because the bit wants to follow the part of the hole already there since it is easier? At what hole size would that runout start to effect me? Like, it says for a 0.3mm tapped hole I need to drill 0.24mm.

Maybe I am overthinking it. I do apologize my knowledge on machines is not that great.

Thank you.
- Gavin

 

[ShopShoe]

More photos, including of the whole machine, might help us troubleshoot the vibration problem at least.

On the runout issue, I personally can't say any more than to ask you if you have used it enough to see if you can successfully use it do do the work you want to do. If you can use it for your purposes the numbers alone may not be a reason to panic.

I would not start with filing or modifying collets: I would consider other sources of problems first.

--ShopShoe

 

[Gavin1024]

More photos, including of the whole machine, might help us troubleshoot the vibration problem at least.

On the runout issue, I personally can't say any more than to ask you if you have used it enough to see if you can successfully use it do do the work you want to do. If you can use it for your purposes the numbers alone may not be a reason to panic.

I would not start with filing or modifying collets: I would consider other sources of problems first.

--ShopShoe

You can find images of my personal machine here: Hamilton Sensitive Drill Press - USA

Though those images are before the belt and idler replacements. Here is one updated image.

More photos, including of the whole machine, might help us troubleshoot the vibration problem at least.

On the runout issue, I personally can't say any more than to ask you if you have used it enough to see if you can successfully use it do do the work you want to do. If you can use it for your purposes the numbers alone may not be a reason to panic.

I would not start with filing or modifying collets: I would consider other sources of problems first.

--ShopShoe

you can find images of my personal machine here Hamilton Sensitive Drill Press - USA

Though those images are from before idler and belt replacements. I have attached one picture below.

 

[clockworkcheval]

Any drill will follow its point. So starting with a sturdy spotting drill top angle 120 degrees is good practice. When you clamp especially the smaller diameter drills at maximum length there is ample flexibility to follow the spot.
Apart from runout there is the issue of non-parallelism between theoretical centerline and centerline drill. This causes increasing runout at drilltip at increasing length of drill. So minimum runout at the tip of a 3 mm drill may mean a lot of runout at the tip of a 6 mm drill. The upshot is that tinkering with collets is often not effective. A simple strategy is to clamp a drill rod with your most popular diameter in its fitting collet and then to shift the position of the colletholder in the arbor till you have minimum runout at drilltip - and mark that relative position.

 

[clockworkcheval]

And of course meticulous cleaning of all cones and cone-bearing surfaces at each change of collet or chuck.
As for vibration I would mistrust the bearings. Check this at speed by pressing a small diameter steel rod between bearing housing and your front teeth - very sensitive!

 

[ShopShoe]

clockworkcheval's advice is excellent. Definitely check the bearings and make sure the colletholding system parts are clean.

Don't forget to check the motor bearings and make sure the motor pulley is concentric and balanced: It's surprising what vibration can come from a poorly-made and unbalanced pulley. Since your motor is mounted to the baseboard vibration will be transmitted to the rest of the machine.

Can you put parts and assemblies from this machine into a lathe between centers for individual testing outside of this machine?

--ShopShoe

 

[BaronJ]

Hi Gavin, I'm not going to get involved in a discussion about run out !
However single phase motors do vibrate and this can be an issue, three phase motors less so. DC motors don't vibrate but other parts of the machine may. Out of balance pulleys, belts not quite as tight as they should be.

 

[Gavin1024]

The upshot is that tinkering with collets is often not effective.

I'm sorry I don't quite understand. I just assume collets would be better, I suppose. As I do also see them on premium sensotive drill presses such as here and here. I almost won a Levin, but I was outbid by $50. Anyways I digress. If I want to drill a locationally accurate hole, but I have runout of 0.1mm, would it actually be the case that the drill bit just flexes to follow the center punch? I can ream afterwards as well.

My plan to setup was to mark the hole location, automatic center punch, then place the part flat onto the table under clamps but with no force (piece can still move), load a short rod with a point into the drill, then lower it over the piece and have the drill itself move the piece to center it (the workpiece is very light weight). Then set the depth stop and clamp the work down. I think the works should then be "perfectly" centered above the center punch?

I just do not want the location or size of the hole being messed up if I am drilling 0.3mm - 0.5mm holes. I didn't know how 0.1mm runout effected that, and I thought that lower runout would be better.

Don't forget to check the motor bearings and make sure the motor pulley is concentric and balanced: It's surprising what vibration can come from a poorly-made and unbalanced pulley. Since your motor is mounted to the baseboard vibration will be transmitted to the rest of the machine.

--ShopShoe

The motor appears to be fine. Running just the motor with no pulley has vibration of course, but a very low acceptable amount I would say.
The idler bearings, despite being brand new and just purchased, do have a slight play in them. I am not sure if it comes that way by design for clearance, or if that is contributing to issues. I replaced the bearings with the exact spec ones that were stock on the machine. Which I admit were a very low grade bearing. I assumed it did not matter since it was just changing the direction of the belt, and not something as critical like a spindle bearing.

The machine definitely has way more vibration at the spindle / housing when turning.

And of course meticulous cleaning of all cones and cone-bearing surfaces at each change of collet or chuck.
As for vibration I would mistrust the bearings.

I would like to inspect and potentially replace the bearings, but I have no press. I have seen videos online of people removing bearings from old lathes that were constructed in a similar way, by placing a block on the spindle and hitting it with a mallet. I however, am skeptical to try this myself. I do not want to damage or bend any parts. Unless guarantied a safe / common thing to do.
If I break a major component of this drill, I am not in a position to purchase another one at the moment. And I have a few projects pending on this machine to work well.

edit:
idler wheel bearings are 6200-2Z; ABEC-1.
The stock bearings were Fafnir 200KD.

 

[minh-thanh]

And then I was thinking, how much does this runout actually effect me in my operations? For example this tapping set I have says if I want to tap for a 0.5mm threaded hole, I need to drill a 0.4mm hole. If the difference here is only 0.1mm, does my 0.1mm+ runout effect that any? Or is this a case where 0.1mm runout doesn't mean the hole size varies by 0.1mm, because the bit wants to follow the part of the hole already there since it is easier? At what hole size would that runout start to effect me? Like, it says for a 0.3mm tapped hole I need to drill 0.24mm.

Maybe I am overthinking it. I do apologize my knowledge on machines is not that great.

Thank you.
- Gavin

My way is to drill and tap with small diameters - But I haven't done it with holes that are too small like yours
Usually the hole being drilled is always larger than the drill bit so first I usually use a slightly smaller drill bit, then drill with the drill bit according to the diameter I need and tap.
For M3 case: first 2.3 mm - then 2.4mm and tap
Similar to M2..
I usually test drill on a sample of the same material as the workpiece

 

[clockworkcheval]

My sequence for the drilling of small precise holes is 1) position the component very precisely on the drill press 2) mark the hole with a stiff short spotting drill 3) drill the hole peckering at high speed.
Free hand centerpunching will give you an average deviation of position of up to 0,3 mm. Yes, a small diameter drill will flex to follow its point. Reaming will make a nicer surface hole with a better defined diameter but will not change the position of direction of the hole in any way.

 

[ShopShoe]

I would also suggest you try the spotting drill method of locating your hole. I read you have an "automatic" center punch. I have a couple of those and I think they are great for larger work, but I have problems getting hole locations spotted with them on smaller work pieces. I suggest getting one or two high quality center punches. If you watch some of the YouTube videos made by experienced machinists you will find that they locate-punch a spot, then check/measure and hit it again with the punch, "steering" it a little bit as they do so. I am working to develop this skill and find that my accuracy is improving. Another old-timer trick is to actually locate the punch on the marked-up workpiece with a magnifying glass.

By the way, spotting drills are very short twist drills that have precision-ground tips and are designed for locating spots for drilling hole with regular drill. Center drills are made for drilling holes in the ends of bars on the lathe for locating a center for turning or tailstock support. Center drills are often used for spotting, but may not be as good as true spotting drills. Whatever: They are both cheap enough that you can buy them for experimental purposes. I also appologize if I am telling you what you already know.

Examples of each at links below. I have no connection to the vendor other than customer on occasion.

https://www.kbctools.com/itemdetail/1-090-001
https://www.kbctools.com/itemdetail/1-044-025
Hope this helps.

--ShopShoe

 

[Gavin1024]

My sequence for the drilling of small precise holes is 1) position the component very precisely on the drill press 2) mark the hole with a stiff short spotting drill 3) drill the hole peckering at high speed.
Free hand centerpunching will give you an average deviation of position of up to 0,3 mm. Yes, a small diameter drill will flex to follow its point. Reaming will make a nicer surface hole with a better defined diameter but will not change the position of direction of the hole in any way.

interesting. I think I will pick up a 0.4mm carbide drill from mcmaster. Still 3mm shank, but the cutting length is a bit shorter at 4.8mm.
I see what you mean about the center punch. How can I accurately center my workpiece to drill on the intersecting scribe in the drill? I do have one of those small usb microscopes set up to see what I am doing, but I still find it hard to truly center. Maybe if I move the microscope around the piece to view it from different angles?

By the way, spotting drills are very short twist drills that have precision-ground tips and are designed for locating spots for drilling hole with regular drill. Center drills are made for drilling holes in the ends of bars on the lathe for locating a center for turning or tailstock support. Center drills are often used for spotting, but may not be as good as true spotting drills. Whatever: They are both cheap enough that you can buy them for experimental purposes. I also appologize if I am telling you what you already know.

Examples of each at links below. I have no connection to the vendor other than customer on occasion.

https://www.kbctools.com/itemdetail/1-090-001
https://www.kbctools.com/itemdetail/1-044-025
Hope this helps.

--ShopShoe

ohh I did not realize this. I did use a center drill, not a spot drill. I'll pickup a spot drill and try it out. Thanks!

 

[krypto]

How are you going to use a spotting drill for a tiny .4mm (1/64") hole? That's not how you do it for such tiny holes, you use a small carbide bit and punch it through.



This is me drilling a .3mm hole in a 3D printer nozzle. Actually widening a .2mm hole to .3mm because blank nozzles seem to be impossible to find. Notice I'm using a fixture to center and hold the work.

The Dumore is running at 17000 RPMs, uses a Jacobs chuck with no visible run-out nor does the drill press have any vibration to speak of. I still have decent vision, but normally I'm using an Optivisor when drilling these tiny holes but the camera was in the way for this video.

What are you drilling and tapping that uses a microscopic .5mm thread? Punch marks with center drills plus a float lock vise work fine on work for a normal sized drill press, but when you are doing such tiny holes you have to change techniques.

 

[Gavin1024]

How are you going to use a spotting drill for a tiny .4mm (1/64") hole? That's not how you do it for such tiny holes.

I'm not trying to seem sarcastic, but if that's not how you do it, then what is the purpose of the spot drill that exist at that size? I see spot drills from 0.1mm to 1mm. etc. Or do you just mean it's usually not necessary?

What are you drilling and tapping that uses a microscopic .5mm thread?

It is a jumper (a spring, of sorts) for a wristwatch. And the main reason I am trying to be as locationally accurate as I possibly can, is because it requires two screws. So if I tighten down both screws. but they aren't really centered above the two jumper holes (a set distance from each other, I feel it would cause unwanted issues. I am already using a tool to approximate the scribe marks for where the holes should be. I just need to make sure to drill where they are.

The holes in the jumper are around 0.6mm in diameter, so for this, I have chosen to use a 0.5mm screw (0.125mm pitch. Aparently there is another .5mm with a different pitch floating around), which means I need to drill 0.4mm (according to the manufacture of the tap).
The screws are 2mm in length (I will cut them) with a slotted counter sunk head (the head going from 0.5mm to 0.94mm at it's widest). Which I think should secure it.
I ask here on this forum, because I feel many people in this community are more familiar with small scale parts, versus others. And while there are forums for watch repair, it is much less common to find information on the machining portion of work.

I have attached an image of the jumper.

 

[krypto]

Your not going to find many people that are working in such tiny sizes with model engines as it's not fun. I curse when I need to drill and tap 2-56 and that's 1.78mm, three times larger than the .5mm you are talking about.

If I had to make this part, I would get the shape of the part close and then glue (CA) it to a sacrificial piece of aluminum. Using the DRO on the mill, it would be easy to get the hole spacing perfect. I would then use the carbide drills I talked about early to make the holes. Using a tap follower and being extremely careful, I might get both holes tapped without hearing the snap of a M0.5mm tap. It's a good idea to buy the 5 pack.

Doing this manually with punches and a scale is going to be challenging to hit the tolerances. Good luck!

 

[ChazzC]

By the way, spotting drills are very short twist drills that have precision-ground tips and are designed for locating spots for drilling hole with regular drill. Center drills are made for drilling holes in the ends of bars on the lathe for locating a center for turning or tailstock support. Center drills are often used for spotting, but may not be as good as true spotting drills. Whatever: They are both cheap enough that you can buy them for experimental purposes. I also appologize if I am telling you what you already know.

--ShopShoe

The big advantage of spotting drills (in the “normal” sizes) is that they are available with 120 degree points - very close to 118 degrees - whereas center drills are 60 degrees.

 

[Peter Twissell]

I use the point of a centre drill for spotting.
The point is 118 or 120 degrees and the body of the centre drill makes it very stiff.
I don't centre punch. I align the point of the spinning centre drill with the scribed mark and touch on, just enough to make a mark, then adjust as necessary using magnification as required.
It is only necessary to make a slight simple to give the drill a starting point.
This process guarantees that the centre is exactly where the drill will be, so the hole will be straight.

 

[krypto]

The big advantage of spotting drills (in the “normal” sizes) is that they are available with 120 degree points - very close to 118 degrees - whereas center drills are 60 degrees.

Yes, You can get spotting drills in 90, 120 and 140 degree angles. Using a 120 degree point spotter, a regular drill with then be started by the central portion (not the edges) while allowing for the chisel point which should allow for the straightest hole.

Having said that, I rarely use spotting drills and tend to use center drills instead. With spotters and small holes, I have a tendency to "over drill" and make the dimple wider than it should be. You can buy small diameter spotters, but then they aren't very stiff either which makes them somewhat useless. For small holes, what you want is a spotter with a fat main body tapered to a small diameter tip which almost exactly describes a center drill. Like Peter said, I just "use the tip" of the center drill and it seems to always work fine.

The 90 degree spotters are preferred by the CNC guys so they can spot and chamfer in one op. Like step drilling, they are losing the guidance of the drill tip. Sometimes "the book" gets thrown out the window for convenience and nothing is lost.

 

[Gavin1024]

Thank you all for the help. Also, I do think I found a major source of the vibration and runout from when the machine is running. If you look at the schematics in the manual here , it seems to be that there is a lot of play between the column and the bar that is driven by the handle / ratchet system. I am able to easily move it back and forth towards the ratchet driving wheel (directly backward away from the spindle) by 0.8mm!!!

So when the machine is running, it isn't necessarily deflecting 0.08mm out from where it should be, but the vibration from this play is still shifting everything slightly. I think the amount and direction also changes based on how far down I have driven the bar. Unfortunately I don't see any way or know how I would get rid of this play.
To recap, the top of the spindle that is connecting to the casting that connects to the bar that is driven by the ratchet wheel can move 0.8mm easily, while the bottom of the spindle connected to the main housing that is stationary on the main column stays in the same position, and I assume just pushes against the bearings when the top moves.

edit:
edit2: in the video I meant to say 0.08mm, not 0.8mm. However after measuring better, it's actually 0.15.

 

[Bentwings]

I'm sorry I don't quite understand. I just assume collets would be better, I suppose. As I do also see them on premium sensotive drill presses such as here and here. I almost won a Levin, but I was outbid by $50. Anyways I digress. If I want to drill a locationally accurate hole, but I have runout of 0.1mm, would it actually be the case that the drill bit just flexes to follow the center punch? I can ream afterwards as well.

My plan to setup was to mark the hole location, automatic center punch, then place the part flat onto the table under clamps but with no force (piece can still move), load a short rod with a point into the drill, then lower it over the piece and have the drill itself move the piece to center it (the workpiece is very light weight). Then set the depth stop and clamp the work down. I think the works should then be "perfectly" centered above the center punch?

I just do not want the location or size of the hole being messed up if I am drilling 0.3mm - 0.5mm holes. I didn't know how 0.1mm runout effected that, and I thought that lower runout would be better.

The motor appears to be fine. Running just the motor with no pulley has vibration of course, but a very low acceptable amount I would say.
The idler bearings, despite being brand new and just purchased, do have a slight play in them. I am not sure if it comes that way by design for clearance, or if that is contributing to issues. I replaced the bearings with the exact spec ones that were stock on the machine. Which I admit were a very low grade bearing. I assumed it did not matter since it was just changing the direction of the belt, and not something as critical like a spindle bearing.

The machine definitely has way more vibration at the spindle / housing when turning.


I would like to inspect and potentially replace the bearings, but I have no press. I have seen videos online of people removing bearings from old lathes that were constructed in a similar way, by placing a block on the spindle and hitting it with a mallet. I however, am skeptical to try this myself. I do not want to damage or bend any parts. Unless guarantied a safe / common thing to do.
If I break a major component of this drill, I am not in a position to purchase another one at the moment. And I have a few projects pending on this machine to work well.

edit:
idler wheel bearings are 6200-2Z; ABEC-1.
The stock bearings were Fafnir 200KD.

I always use a center drill carefully just touch the punch mark you can move it slightly then lightly center drill down to the thicker shank spot. This should give a pretty good starting point . If the drill is very small it still can bend a little as it begins the cut . If you must have a very close hole you may just have to drill then bote to finish I don’t like this but you have to do what you need . I generally get pretty good holes just being extra careful with feeds and speeds .