Drilling 40xD holes in UHMW. How to not get melty melty

[13engines]

I don't seem to be getting any backup on my earlier idea so I'm going to try again, because short of a gun drill with high pressure coolant, I think it has a high chance of doing it for the OP.

Using that taper length or longer parabolic drill like OX suggested, take a scrap block of your UHMW and program a succession of holes with ever increasing feed rates. Starting at maybe 10 per all the way up to 60-70 per. (maybe more) Start out going only 1 1/2 -2" deep so you can observe the chips. Or chip ropes rather. You'll soon find out what looks like it will work. Increase your depth once the idea of a working set of numbers develops. Use G82 with the shortest possible dwell (P) call to break off the chips. (No pecking) Hopefully they will come most if not all the way out with the drill shank. Start your testing even as low as 100rpms. This is very soft plastic. You really don't need to think about it at all like drilling aluminum or steel. It's even better then machining Aluminum, in how much you can get away with murder. Again... watch out for shrink back on your diameter.

Note that I've never drilled a hole with the particulars the OP is dealing with, but I do know you can plunge a parabolic into UHMW mercilessly.

I don't machine UHMW or any plastic with coolant, but what the hell... throw some coolant at it if you want. Couldn't hurt.

 

[Mustang Jack]

I don't know if you guys have WNT or ceratizit in the US but they do ultra long series carbide drills with thru coolant it might be worth checking them out and seeing what they have to offer

 

[rk9268vc]

Update
Customer let me make this part out of Delrin which helped A LOT. Like game changer.
Drilled the hole and turned out perfectly
Had 2 parts, each with 2 of these holes in them. All 4 holes worked well

Used this drill from mcmaster
Object moved
McMaster part 2854A443
The shank is 2 thou smaller than the flutes for clearance
cut the drill down to about 8in length

Ran it dry, no coolant, no air.
Full retract, 40thou peck. Paused every 5 pecks for cooling

Other than a few hairs at the hole opening, it turned out beautiful. Nice chips.
Had a hole drilled in a later OP that intersected the tip of this hole and it looks like it only wandered about 20 thou over the about 6 in deep hole.

Thanks for all the help and suggestions guys, will definitely check out parabolic drills for future uses.

Parts turned out good, here are pics. The holes are drilled from the back and intersect a few holes for pneumatics


Not going to post pics of setup, so this thread doesnt turn into another discussion about how much my mill sucks haha

 

[Ox]

Note:

Most all drills have back taper.



--------------------

Think Snow Eh!
Ox

 

[TeachMePlease]

I don't know if you guys have WNT or ceratizit in the US but they do ultra long series carbide drills with thru coolant it might be worth checking them out and seeing what they have to offer

Ceratizit makes great tools. But buying a Ceratizit solid carbide drill for making a couple holes in plastic is akin to buying a brand new Porsche to drive to church once a week....

 

[Ox]

Ceratizit makes great tools. But buying a Ceratizit solid carbide drill for making a couple holes in plastic is akin to buying a brand new Porsche to drive to church once a week....

Well, back before your time, that was considered acceptable justification in S California.
Even if you were a little old lady.


--------------------

Think Snow Eh!
Ox

 

[DDoug]

Well, back before your time, that was considered acceptable justification in S California.
Even if you were a little old lady.


--------------------

Think Snow Eh!
Ox

Especially when you need to get to Church RIGHT NOW !.....

 

[Micmac1]

4mm .1575 dia Guhring Thru Coolant Gun Drill 9056470040000

 

[Strostkovy]

Epoxy together a block of stir sticks. No drilling needed.

Or hog out the back and only leave holes on the front.

I get you personally can't make these changes, but I feel like this is more an engineering problem.

 

[CITIZEN F16]

Update
Customer let me make this part out of Delrin which helped A LOT. Like game changer.
Drilled the hole and turned out perfectly
Had 2 parts, each with 2 of these holes in them. All 4 holes worked well

Used this drill from mcmaster
Object moved
McMaster part 2854A443
The shank is 2 thou smaller than the flutes for clearance
cut the drill down to about 8in length

Ran it dry, no coolant, no air.
Full retract, 40thou peck. Paused every 5 pecks for cooling

Other than a few hairs at the hole opening, it turned out beautiful. Nice chips.
Had a hole drilled in a later OP that intersected the tip of this hole and it looks like it only wandered about 20 thou over the about 6 in deep hole.

Thanks for all the help and suggestions guys, will definitely check out parabolic drills for future uses.

Parts turned out good, here are pics. The holes are drilled from the back and intersect a few holes for pneumatics
View attachment 344161

Not going to post pics of setup, so this thread doesnt turn into another discussion about how much my mill sucks haha

Thanks for the update, those are always appreciated. It usually is best when starting to steer the customer away from a lousy to machine material is to mention the cost savings, often that can be mutually beneficial. The end result can be billing a smaller amount at a higher per hour profit.

 

[TeachMePlease]

Well, back before your time, that was considered acceptable justification in S California.
Even if you were a little old lady.


--------------------

Think Snow Eh!
Ox

Perhaps in the vicinity of Pasadena?

 

[CITIZEN F16]

Perhaps in the vicinity of Pasadena?

A lot of people confuse Jan & Dean with the Beach Boys.

 

[rk9268vc]

Thanks for the update, those are always appreciated. It usually is best when starting to steer the customer away from a lousy to machine material is to mention the cost savings, often that can be mutually beneficial. The end result can be billing a smaller amount at a higher per hour profit.

The problem is the engineers seeing that UHMW is cheaper to buy the material than delrin.
This often makes them choose uhmw over delrin for "cheaper" parts that dont matter as much
The problem is then the buyer thinks its a "cheap" part and get sticker shock because they dont know that uhmw sucks to work with, especially when the print has crazy stuff in it

For example this part they are asking a quote on today.
look at those tolerances.
in UHMW.
look at that material removal.
this thing is going to be warp city.

and qty 1 of course

wont let me add the pdf because size too big and shrinks image, but hope you can see lol

 

[CITIZEN F16]

The problem is the engineers seeing that UHMW is cheaper to buy the material than delrin.
This often makes them choose uhmw over delrin for "cheaper" parts that dont matter as much
The problem is then the buyer thinks its a "cheap" part and get sticker shock because they dont know that uhmw sucks to work with, especially when the print has crazy stuff in it

For example this part they are asking a quote on today.
look at those tolerances.
in UHMW.
look at that material removal.
this thing is going to be warp city.

and qty 1 of course
View attachment 344234
wont let me add the pdf because size too big and shrinks image, but hope you can see lol

Better you than me. I hope for your sake you are making great money running parts like those, like I have said many times I have a variable shop rate, depending on degree of difficulty, that part you are quoting would get high shop rate and I would pad the time to scrap a few. Good luck!

 

[rk9268vc]

Better you than me. I hope for your sake you are making great money running parts like those, like I have said many times I have a variable shop rate, depending on degree of difficulty, that part you are quoting would get high shop rate and I would pad the time to scrap a few. Good luck!

I'm still trying to figure out how much to quote that part for. Qty 2 now
What would you quote it as? They dont supply CAD until I get the PO so I cant just throw it in xometry to see ballpark
thx

 

[mhajicek]

Well, back before your time, that was considered acceptable justification in S California.
Even if you were a little old lady.


--------------------

Think Snow Eh!
Ox

I'm still trying to figure out how much to quote that part for. Qty 2 now
What would you quote it as? They dont supply CAD until I get the PO so I cant just throw it in xometry to see ballpark
thx

I don't get out of bed for less than $500.

 

[kustomizer]

I don't get out of bed for less than $500.

I do, but then I have to decide if the walk to the shop is more interesting than the walk to the river

 

[rk9268vc]

Better you than me. I hope for your sake you are making great money running parts like those, like I have said many times I have a variable shop rate, depending on degree of difficulty, that part you are quoting would get high shop rate and I would pad the time to scrap a few. Good luck!

I got the job for $700

now I just have to figure out how the heck im going to do it haha