Milling and mounting for a red dot

[ditcherman]

CNC is only as good as the programmer, and how well the machine is set up.
If the machine has any slop, it can ruin a project with tight tolerances. If cutter dia.
isn't exact, it to can ruin the project with those tight tolerances, or at minimum if it's
undersized, is cause a program adjustment. CNC is great for production runs, once dialed in, but for a one off, I would choose manual.
With manual machining, the tolerances can be adjusted on the fly, without having to change the toolpaths.
I'm guessing it's just a square dado being cut in the slide? I'm sure you can do it.

Maybe AllenM's opinion would be different.

Interesting, that logic makes sense. CNC's aren't magic I guess.
There is a radius at the front, hard to see here, but this is my scrap piece of steel test piece.

 

[Lpherr]

Interesting, that logic makes sense. CNC's aren't magic I guess.
There is a radius at the front, hard to see here, but this is my scrap piece of steel test piece. View attachment 250750

A 90* square end mill, will cut the corners square. There are roughing/finishing high helix cutters that give a good finish.
Personally, I would cut perpendicular to the slide, with a 75%-80% stepover, and the finish cut around .010-.015 for a nice clean flat.
Again, JMO.
What you have looks good.

 

[nucular]

A 90* square end mill, will cut the corners square. There are roughing/finishing high helix cutters that give a good finish.
Personally, I would cut perpendicular to the slide, with a 75%-80% stepover, and the finish cut around .010-.015 for a nice clean flat.
Again, JMO.
What you have looks good.

Yeah that's begging for a finish cut. What speed/feed are you running? Lubricant?

 

[ditcherman]

A 90* square end mill, will cut the corners square. There are roughing/finishing high helix cutters that give a good finish.
Personally, I would cut perpendicular to the slide, with a 75%-80% stepover, and the finish cut around .010-.015 for a nice clean flat.
Again, JMO.
What you have looks good.

Thanks for the advice!
I cut that in different directions on each cut, and that last cut was .038 with a 3/8 carbide that was not in the best shape. I have two new ones to use when the time comes.

I cut the front radius (2.06 +/-) with a fly cutter, i'm not sure how to cut a radius with a regular cutter and get a consistent edge, at least with what I have, skill wise and backlash wise .

 

[ditcherman]

Yeah that's begging for a finish cut. What speed/feed are you running? Lubricant?

Agree, by that point I knew my math was right and I was just in a hurry to move on to get the holes marked, drilled, and tapped.

I honestly can't tell you what speed I'm running because I'm running the mill and lathe on VFD's, single phase availability only. But had the VFD roughly turned up all the way, high range cranked pretty far down, best guess is 800-1000 rpm. 3/8 carbide, no lube, with a pretty beat up mill, saving the good ones for the real thing. Kinda wanted to see how it did with no lube, even though I know the slide will be much different steel.

ETA My father in law retired as a tool and die maker (schwizters, Mallory) and has helped me a bit get a feel for some things.

 

[Lpherr]

Thanks for the advice!
I cut that in different directions on each cut, and that last cut was .038 with a 3/8 carbide that was not in the best shape. I have two new ones to use when the time comes.

I cut the front radius (2.06 +/-) with a fly cutter, i'm not sure how to cut a radius with a regular cutter and get a consistent edge, at least with what I have, skill wise and backlash wise .

A rotary table, but you probably don't have that, and they aren't inexpensive.

 

[ditcherman]

A rotary table, but you probably don't have that, and they aren't inexpensive.

Ah, I do actually but haven't used it yet, just got it a week ago. And it's a Palmgren, 8", older but from a lab setting with very little use. I've been reading some not so great things about the Palmgren, and don't have anything yet as far as workholding that will fit it. So pretty unsure of it's abilities yet.

 

[MCgrease08]

I’ll do more checking on the bottom though.

 

[ditcherman]

I obviously didn’t check your bottom before I shot you a price, did I?







We’re talking about truck frames now! Ya wierdos!

 

[ditcherman]

Appreciate all the encouragement and advice (except for @MCgrease08 of course), got this milled this afternoon.




Now to try my hand at some stenciling.

 

[Lpherr]

Appreciate all the encouragement and advice (except for @MCgrease08 of course), got this milled this afternoon.

View attachment 251102


Now to try my hand at some stenciling.

That looks pretty clean. How's the fit?

 

[ditcherman]

That looks pretty clean. How's the fit?

Im happy with it, it won’t move enough to be able to break the bolts. As you stated above, I kept going on the mill for a hand fit, stopped just short of my measurement and started test fitting.
Spent quite a bit of time trying to make sure it was flat, but it was the optic base that is letting light shine through. I did clean it up with a file and then polish it a bit, didn’t get rid of all the tool marks but I think it’s fine.
Time will tell.

 

[ChuckZ]

Even without CNC you should be able to fit it fairly close on both ends.
The main thing is using a sharp enough end mill that it doesn't leave a radius at the bottom corners of the cut so that to optic can't sit flat.
Once cut be sure to visually make certain there is no gap under the optic before screwing it down.

The bosses are nice a press fit is nice but the screws do hold well.....

Hey man, I am new to this forum. I saw you are the guy to get in contact with about doing custom work. Can you send me a message?

 

[ditcherman]

Hey man, I am new to this forum. I saw you are the guy to get in contact with about doing custom work. Can you send me a message?

He probably can’t, until you have 50 posts or become a site supporter.
If you google Diamond Collision in Avon you can get his info.
He’s great, don’t hesitate to use him.

 

[ChuckZ]

He probably can’t, until you have 50 posts or become a site supporter.
If you google Diamond Collision in Avon you can get his info.
He’s great, don’t hesitate to use him.

Thank you man, I appreciate the help!

 

[russc2542]

If you have to pick, flush with the forward edge. As the linked article with the accelerometer above shows, the hardest (and more of them) hits are firing and slamming closed. Hitting the rear end of travel has less shock some deceleration from the recoil spring and shock absorbsion from the frame being in your hand and moveable.

When AllenM cut my CZ for a Holosun, it was flush on both ends, not quite interference fit. The screws just held it down. perfect.

 

[Vimace]

I need to schedule a slide cut with AllenM for one of my Gen3 Glocks.

I'm thinking the same...

Let us know how it turns out for You !!!

Sent from my SM-N950U using Tapatalk

 

[ditcherman]

Finished product…
Titanium slide with Kobalt Kinetics green frame.
Slide might look better in Tungsten, we’ll see how this grows on me.

I gave up on my Kryptek stenciling idea, it just doesn’t fit this gun and I need more experience on something simpler/less valuable.

One interesting thing about the Eotech is that the mounting screws are tapered head, so they center the optic on the holes, unlike what I’ve seen before where you have some wiggle room to center the optic with a flat bottom screw head.

 

[T-DOGG]

I hope you don't mind @ditcherman, but I'm going to reveal my little journey inspired by you.

I'll go ahead and reveal my intentions. This all started because I have an extra Holosun red dot that I decided I want to install on my Witness .45acp. Being that I prefer to be self-sufficient as much as possible in my endeavors in life, I really didn't want to farm out the optics cut this time. No offense to AllenM or anyone else in that regard. Allen has performed several optics cuts for me in the past and I highly recommend him. I want to learn the way, but I'm on a budget. Research began on converting my drill press to a pseudo mill, so here I am.

Quick background. I have a Wen 10" drill press that has a low number of hours on it, so it's in great condition. I can adjust speed up to 3100 rpm. I bought an XY table (Vevor brand), a milling vise (Kurt style Vevor brand) and an end mill suitable for cutting steel (AlTiN Coating). Then I began to realize I needed more if I was going to really try and pull off an optics cut. The plan isn't to get perfection, I'm hoping to get good enough where I can do some final clean up with files and sandpaper. Not looking to go commercial/professional here, more like professional amateur for my own fun (and learning). Again, I'm on a budget. I don't have finances or room for a Bridgeport. The cheapest mini-mill I can find is around $800-$900 and the slightly larger ones from Grizzly and such start getting into $2k on up. I've seen used Bridgeports in the $1500 to $3000 price range, again no money or room for that on top of whatever is involved to convert them to single phase 220V.

The drill press (pseudo mill) upgrades continue with an 8" Vevor brand rotary table, 123 blocks and t-slot hold down kit on order. Hoping to have my spindle threaded this week for use with the ER-16 collet holder. Today's goal is to find a replacement column/tube that is taller, need about 3-4" of increased height on the press. First option is contacting the manufacturer, Wen. Second option is going to the local metal supply house. It's not a commonly used size and has an OD of 2.28" with an ID of 2.11". If I go the metal supply house route, it looks like 1020 DOM mild steel tubing with an OD of 2.5" and ID of 2.26" will have to be used as a sleeve/extension piece onto my existing column, which will require some fitting because the ID is smaller than the OD of my current tube by about .020". Not ideal, but it gives me easily adjustable height by still using my press's table that has a crank/rack setup.

To clarify, for our folks with actual machinist experience, I am well aware of the difference between a drill press and a mill. I did the amount of research I determined necessary. There are other folks that have converted their drill press for milling operations. I read their builds and watched their videos, multiple times. The two common areas of concern seem to be 1) The tapered mounting of the cutting tool head causing the tool head to fall off with too much side load pressure. I am addressing this by having an extra spindle, that's originally a Jacobs JT-33 taper, threaded 1/2-20 for use with an ER-16 collet holder purchased from Hemly Tool Supply out of Ohio. 2) The use of angular contact bearings to withstand increased radial load (side load). The bearings used in the drill press are 6201 and 6203 deep groove ball bearings, which are designed to withstand axial and radial loads. I'm familiar with these bearings because they've been using them in the transportation industry for years in pulleys and other belt driven components. In fact, one of the people who modified their press stated the angular contact bearings were not required and did a direct comparison, showing no difference in the milling surface produced. Even if I developed issues with my bearings, they are cheap and readily available along with being easy to replace.

The nice thing about this upgrade to my press is that this allows me to perform things I've done before faster and easier along with opening the door to future projects I previously discarded. I dabble in woodworking, car repairs, home repairs and other various chores a family man with a house might encounter.


ER-16 collet kit: https://www.ebay.com/itm/184143565063
End Mill: www.amazon.com/dp/B097CYX5RV?psc=1&ref=ppx_yo2ov_dt_b_product_details
XY Table: www.amazon.com/dp/B0713YLS3K?psc=1&ref=ppx_yo2ov_dt_b_product_details
Milling vise: www.amazon.com/dp/B07F8PBQRH?psc=1&ref=ppx_yo2ov_dt_b_product_details
Parallel bars: www.amazon.com/dp/B00QSS3OV0?psc=1&ref=ppx_yo2ov_dt_b_product_details
Test indicator: www.amazon.com/dp/B07D96JP7K?psc=1&ref=ppx_yo2ov_dt_b_product_details
Dial indicator: www.amazon.com/dp/B07C756TCM?psc=1&ref=ppx_yo2ov_dt_b_product_details
Rotary Table: www.amazon.com/dp/B07YMQ72MQ?psc=1&ref=ppx_yo2ov_dt_b_product_details
123 blocks: www.amazon.com/dp/B0000AY61E?psc=1&ref=ppx_yo2ov_dt_b_product_details
Clamping kit: www.amazon.com/gp/product/B00N415N6I/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1


Here are some pictures of my project mocked up at the moment:

 

[T-DOGG]

I guess I should mention that I plan to make very light cuts using the pseudo mill, especially with steel. I don't care if takes longer, it's not a race.