The Home Machinist!

Yep! What Glenn said! The only negative I can think of would be that the spinning collar could leave a pattern on the face of the part.

H

Harold_V wrote: ↑Mon Feb 20, 2023 4:34 pmThe only negative I can think of would be that the spinning collar could leave a pattern on the face of the part.

You hold the outside of the cage/collar with your fingers so it does not spin to avoid that.

Harold_V wrote: ↑Mon Feb 20, 2023 4:34 pm Yep! What Glenn said! The only negative I can think of would be that the spinning collar could leave a pattern on the face of the part.

H

Those microstops also come with a nylon 'bumper' which I guess would minimize marring.
I never knew such a thing existed !

jcfx wrote: ↑Tue Feb 21, 2023 6:29 pm Those microstops also come with a nylon 'bumper' which I guess would minimize marring.

Effective within reason. The finish on the copper clad boards isn't likely to respond well to anything that moves, though. Even stationary, it can leave marks due to the soft nature and uniform finish of the board. Spinning, even with a nylon bumper would leave circular marks, albeit very light in nature. It's all a matter of how much can be tolerated. It's not usually a problem in production.

I never knew such a thing existed !

Rarely found in the average shop, and almost never in a home shop. I've not used one in more than 60 years, but they were used daily where I was trained.

They offer one thing that a spindle stop does not, and that's reliable repeatability. Because they gauge depth from the part surface, any variation in part thickness makes no difference. That becomes quite important when one has ±.005" tolerance on the diameter (common for c'sinks where I was trained) and the included angle is excessive (like 100°), the slightest depth difference (easily done with a spindle stop) manifests itself in a ruined c'sink. Such features were critical and often resulted in scrapped components.

On the subject of best kept secrets, one of them, at least in my opinion, is the Wahlstrom drill chuck. How nice it is to be able to change drill sizes without stopping the spindle.

H

Thanks, Harold. No worry about marks in the copper-clad, the panel is covered afterward with a (printed-on), opaque plastic overlay; just a few mils of vinyl with a very aggressive adhesive. Kind of a trick to position it properly, but practice makes perfect, as my mom used to say. I do like the idea of the Microstop device, but would the shroud around it interfere with 'bomb-sighting' the hole to be countersunk? Because the panel is so light in weight, I've found good success in bringing down the countersink slowly, letting the panel 'float' on the drill press table and self-center before being held-down for the cutting. Of course not an issue if the countersink is the 'piloted' variety. I'm really tempted to get one despite success with the lower-tech approach.

Harold_V wrote: That becomes quite important when one has ?.005" tolerance on the diameter.

Also helps if you're trying to install countersunk rivets exactly exactly exactly flush with the surface.

Electrojim wrote: ↑Wed Feb 22, 2023 11:26 am I do like the idea of the Microstop device, but would the shroud around it interfere with 'bomb-sighting' the hole to be countersunk?

No. Like any spinning object with openings, you can still see the target hole. You also get used to the relationship between the stop and the hole quite quickly and the pilot guarantees proper location. A win/win deal if there ever was one, especially on thin panels where there's little to no risk of breaking the pilot.

Because the panel is so light in weight, I've found good success in bringing down the countersink slowly, letting the panel 'float' on the drill press table and self-center before being held-down for the cutting. Of course not an issue if the countersink is the 'piloted' variety.

That's precisely what I mean when I say a person isn't ham handed. Given a little time, a multi-toothed c'sink will generally center on an existing hole, given the opportunity. It may not even be perfect but it will usually be within a reasonable amount so it's functional. I rely on this method, or I often go back and c'sink all holes after drilling by revisiting their location with the screws on my mill. Much easier to hold a critical diameter that way, assuming no Microstop.

I'm really tempted to get one despite success with the lower-tech approach.

If you had the requirement Russ mentioned (flush rivets) you'd most likely need one, and for the reasons I mentioned previously. There was a huge amount of riveting on the Sergeant Missile, with Microstops used for preparing the holes for rivets. They had to be flush. The work was often accomplished by hand, not with machines. Microstops made it easy.
By the way, a pilot is almost mandatory, so if you do give one a go make sure you get the required size. You'll be glad you did.

H

I see that Glen's link to Yardstore has a 'common' microstop for $10 (https://www.yardstore.com/common-microstop-used), although it doesn't have a nylon face. Pardon my ignorance, but does that outer sleeve spin; that is, if you bring the drill press down hard does it want to burrow a 3/4" (or whatever) hole through the work, or is there a bearing in there that permits you to hold the outside stationary? Yardhouse has the piloted countersink too, but the pilot is #27 (0.144) and my holes are 1/8". I saw just the countersink on another site, but it was $20 or so. Still cheap!

Electrojim wrote: ↑Wed Feb 22, 2023 5:30 pm I see that Glen's link to Yardstore has a 'common' microstop for $10 (https://www.yardstore.com/common-microstop-used), although it doesn't have a nylon face. Pardon my ignorance, but does that outer sleeve spin; that is, if you bring the drill press down hard does it want to burrow a 3/4" (or whatever) hole through the work, or is there a bearing in there that permits you to hold the outside stationary?

That's the part Glenn said you put a finger on to stop it from spinning, so, yeah, it (should) have a bearing. I can't speak for anything made today as it's been more than 50 years since I last used one.

Yardhouse has the piloted countersink too, but the pilot is #27 (0.144) and my holes are 1/8". I saw just the countersink on another site, but it was $20 or so. Still cheap!

I suspect that the shank size of the pilot is .125", but I can't be sure. It's been way too long since my last experience and I wouldn't be surprised if it's 3/32". Bottom line is so long as it's not integral with the C'sink, you can make one if necessary. A drill blank would do fine, as would a dowel pin. Even one turned from soft material (drill rod or even mild steel) would work fine, it just wouldn't enjoy the same longevity as one that's hardened.

H

Some Microstops use a bushing but the better ones a bearing. I prefer a bearing for greater repeatability with rivet heads, but for screws a bushing will be fine.

A hand drill simplifies things, as you hold the drill in one hand and the cage in the other. Using a drill press adds a bit of awkwardness as you need to use your third hand to hold the part you are trying to countersink while the other two hands hold the cags and work the drill press quill.

The pilots on the countersinks come in many different sizes.

Here is a 1/8"

https://www.yardstore.com/consumables/c ... -5-16-body

Interesting. I recall the c'sinks accepting removeable pilots with a small set screw on the side of the c'sink. Don't they do that anymore?

H

Edit: I did a search for Microstop c'sinks that accept replaceable pilots. They are available, but the integral pilot seems to be the norm. In their favor, the integral pilot would be nearly impossible to break, unlike the replaceable type.

I will soon be drilling over 300 1/16" holes in a 16 gauge piece of mild steel that will form the bottom of my tender tank, attached with flat head 0-80 screws to a machined recess in the frame around it. This bottom will necessarily be attached to the tender tank last. A Microstop device would be nice to use, as I wouldn't have to concern myself with countersink depth for each hole. I believe that I won't be able to depend upon the bottom plate being hard against the drilling base all the time, and a 1/16" counter sink will probably not have enough downward pressure to force it. The down stop on the Bridgeport or my drill press would not produce accurate counter sink holes. So a Microstop would be just right.

However, one big problem. It does not appear that a Microstop countersink is available with a 1/16" pilot. The smallest pilot shanks available appear to be around 3/32". Any suggestions?