Apologies if this is a repeat question, but which drills/bits are best for making holes in plastic resin or 3D printed materials? I need to make a 4mm wide hole or two, about 3mm deep.
Thank you for any advice.
Mike.
You don't need a special drill bits for plastic, but when drilling plastic I would avoid very high rotational speeds as this can melt rather than cut the plastic.
In addition 3d prints are often quite brittle, so try to support the back of the hole when drilling to avoid the print snapping.
4mm seems quite a big hole to drill in one go, so I would be tempted to go up in steps, for example starting with 1mm, followed by 2 then 3 before finishing off with the 4mm bit. You may not need as many (or start that small), or it may even need some intermediate steps as well.
Finally, I'd be tempted to use a pin vice to drill by hand as you can feel the drill bit bite into the material and you'll be less likely to melt the plastic or break the print, though finding one that will take the bigger (3mm +) size bits might be difficult.
Hope that helps...
About the only thing I can think to add is that general purpose twist drills have quite large flute twist and clearance angles so I would most certainly drill by hand. To hold larger drills I have used a "millie" AKA wheel brace, but rotate the chuck itself by hand and not the crank. As soon as you feel the drill 'bite' back off.
There are special drill bits for different materials with different twist a but they are rarer and more expensive.
If it is not a blind hole but one through 4 mm sheet you could try opening up a smaller hole (that should be easier to drill) with a hand reamer or cutting broach.
Something like this one: Amazon (https://www.amazon.co.uk/QWORK-Tapered-Straight-Handle-Plastic/dp/B086HLMCKD/ref=asc_df_B086HLMCKD?mcid=c31224009d3b3c1aa960537005581279&hvocijid=1595301657328368012-B086HLMCKD-&hvexpln=74&tag=googshopuk-21&linkCode=df0&hvadid=696285193871&hvpos=&hvnetw=g&hvrand=1595301657328368012&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007293&hvtargid=pla-2281435176698&psc=1&gad_source=1)
I use one for enlarging holes in electronics project boxes and so on. The hole will be tapered but working from both sides the taper will be halved.
Cutting broaches have less taper, but the inexpensive sets don't seem to go up to 4 mm. (I found at set at a good price, but didn't notice they were smoothing broaches, not cutting broaches.
Here's a larger set Amazon (https://www.amazon.co.uk/Cutting-Broaches-Jewellery-Making-Postage/dp/B00AZGA8DS?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A34SQMQEWML6D0&gQT=1)
Thanks, Julien and Graeme; I bought a few low-loaders from an online source, but the holes for the bogies are too close to the wagon end, so I need to make new holes to accept the Peco wagon bogie clips. The bed is about 4mm thick. See image below. I'll review the links you sent, but you might have alternative ideas on fixing the bogies...(https://i.ebayimg.com/images/g/uh4AAOSw9IVnvkGS/s-l1600.jpg)
Incidentally, is the only way to post an image via a url, or is the a way to link to an address/file location on my PC?
Hi Mike,
If you are worried about drilling holes in the 3D print, an alternative way to consider for fixing bogies is to use small (size 00) dressmakers press studs. Just glue one part (I would use the female for this and use superglue gel) to the underside of the wagon at the right place, then glue the male (smaller) part to the top of the bogie, bulking it up with a piece of plasticard to get to the right height of top of bogie to base of wagon and that's it done.
You may have to slightly loosen the grip between parts of the press stud by gently sanding (I simply use a nail emery board from Boots) a little around the knob on the male stud (no euphemisms please, behave yourselves at the back.....) to ease the stiffness
I've fitted out a number of both railcar rear bogies and Ratio-bashed coaches this way without problems, and this method comes with the advantage that it provides a degree of lateral and longitudinal movement (ie suspension) for the bogies.
Recommended, hardly costs anything and worth a try!
Mick
Fantastic, Mick - I'll look at them now!
But do you have to then file off the Peco bogie "clip" pair that provides the fixing?
(https://cdn10.bigcommerce.com/s-b9i2gb/products/1355902/images/446394/gr-106_1__17423.1745523006.1280.1280.jpg?c=2)
Cheers!
Quote from: Mike Oehlers on June 15, 2025, 18:28Incidentally, is the only way to post an image via a url, or is the a way to link to an address/file location on my PC?
You can post images directly to the forum, so long as you observe the attatchment size limit (which applies per post)
Also it only allows certain file types (interestingly it "sees" .JPG files, but not .JPEG files - but you can rename them on your machine first)
Also, I have found you can only attach photos using the REPLY button rather than using the "Quick Reply" window at the foot of the page - you then get the option
Click or drag files here to attach them.
From the photo it looks like a filament 3D print in which case brittleness may not be a problem but you may have another issue. When drilling there might be some danger of the filament delaminating if done too roughly.
I wonder if melting the holes would work?
Quote from: Graeme Dunbar on June 15, 2025, 21:40From the photo it looks like a filament 3D print in which case brittleness may not be a problem but you may have another issue. When drilling there might be some danger of the filament delaminating if done too roughly.
I wonder if melting the holes would work?
It's very definitely filamentous! Intriguing - how would you propose to do that (melt holes)?
Quote from: Mike Oehlers on June 16, 2025, 01:46Quote from: Graeme Dunbar on June 15, 2025, 21:40From the photo it looks like a filament 3D print in which case brittleness may not be a problem but you may have another issue. When drilling there might be some danger of the filament delaminating if done too roughly.
I wonder if melting the holes would work?
It's very definitely filamentous! Intriguing - how would you propose to do that (melt holes)?
The facetious answer would be 'with some difficulty'. It would be a lot easier with plenty of bits of scrap to practise on, but I imagine you have one chance to get it right first time.
With plasticard, I would heat up a piece of brass (or similar) tube and press that into the sheet. I'd probably melt the hole first and then cut the plasticard to size around it if I could, but there is not that option here.
Another possibility is to melt a larger hole, fill it with something that is easier to drill and drill it.
Another would be to melt a small hole and enlarge it slowly. A variation, combined with the method above would be to make the hole oversize to take a bushing of say Plasticard tube and pack any gaps with glue.
Another (if it can be hidden) is to glue a very thin reinforcing shim to the surfaces and drill through that.
For melting I'd use an old soldering iron or at least a replaceable bit in a soldering iron and a temperature controlled iron for preference. The usual warnings about fumes etc. apply.
Edit: I've remembered there are videos online of people using similar techniques to melt metal threaded inserts into 3D printed objects. I'll see if I can find a video.
Quote from: Mike Oehlers on June 15, 2025, 19:02Fantastic, Mick - I'll look at them now!
But do you have to then file off the Peco bogie "clip" pair that provides the fixing?
Cheers!
Yes you'd have to file off anything that sticks up above the bogie as the press stud would replace it!
In my railcar underside photo below I have added a small piece of pond lining lead alloy stuff to the bogie for weighting and added some pieces of 20 or 30 thou plasticard to both the bogie and the female stud on the railcar body to get the height right. Don't worry about the N gauge hook coupling! I grew up with the late Dave Scott (Chelthwaite & Beccadale) and Ted Polet (Craigcorrie & Dunlalistair) and others who used/use N couplings for a number of reasons, including cost, if you bash N stock items for 009 use, what is the point of paying extra for couplings when you've already got good ones supplied. There's more good reasons, but here is not the place to launch a huge thread drift debate about choice of couplings!
(https://i.imgur.com/Zqubz8s.jpg)
I've heard that if you use the 'popper'/ snap fastener method and they are too tight to swivel easily then mixing a male' one from a card of them with a 'female' the next size up can solve the problem so long as the little wire spring clip still engages with the stud, e.g.
Hobbycraft (https://www.hobbycraft.co.uk/hemline-assorted-silver-snap-fasteners-20-pack/5671331001.html?glCountry=GB&store=&gad_source=1&gad_campaignid=20489202173&gbraid=0AAAAADnvm3JTmnvu0TISAIO3O5CfgrbxT&gclid=CjwKCAjwgb_CBhBMEiwA0p3oONJMk6VJpHVzGuLWqhhQI-0pSiy0tYl-38AOGPoWSebNTpr3qe3ziBoCxcwQAvD_BwE&gclsrc=aw.ds)
(https://www.hobbycraft.co.uk/dw/image/v2/BHCG_PRD/on/demandware.static/-/Sites-hobbycraft-uk-master/default/dw78d44eb2/images/large/567133_1001_1_-hemline-assorted-silver-snap-fasteners-20-pack.jpg?sw=680&q=85)
(I don't know if it will work with these particular ones.)
Thanks, chaps - I'm going to go down the pin vise/vice (sp?) route to start and if that proves too destructive, I'll try the press-stud method!
Thanks for all the advice - invaluable to have so many experts to call on.
Quote from: Hugh Norwood on June 15, 2025, 21:16Quote from: Mike Oehlers on June 15, 2025, 18:28Incidentally, is the only way to post an image via a url, or is the a way to link to an address/file location on my PC?
You can post images directly to the forum, so long as you observe the attatchment size limit (which applies per post)
Also it only allows certain file types (interestingly it "sees" .JPG files, but not .JPEG files - but you can rename them on your machine first)
Also, I have found you can only attach photos using the REPLY button rather than using the "Quick Reply" window at the foot of the page - you then get the option Click or drag files here to attach them.
Thanks for the response.
I have seen it, but cannot find it now, but what is the attachment size limit (data volume or pixel dimension)?
QuoteI'm going to go down the pin vise/vice (sp?) route
"Vice" in the UK,"vise" in the USA.
It is 300km per post - so you can post as many images as make up to that limit.
When I report the Card SIG and Oldham group meetings, I make sure that none of the images I post are greater than 800 pixels on the longer axis. This tends to produce file sizes of around 100kb. (NB the forum puts the resulting image at the current cursor position in your post, but it is quite easy to move it around the post using cut and paste)
Quote from: JulienW on June 16, 2025, 20:20QuoteI'm going to go down the pin vise/vice (sp?) route
"Vice" in the UK,"vise" in the USA.
See Terry Pratchett's "Going Postal" for more on what might be called "pin vice" <grin>
"300km per post" - that's a long one!
As to Terry Pratchett's Going Postal - I'll ask wife - she'll know what you mean! Although I now know more about your layout. <smirk>
Thanks for attachment info.
M.
kB - you know what I mean <grin>
{as an aside, there's some fuziness over the prefix "k" in computer speak, as it can be used to mean kilo- as in 1000 _or_ 1024 (2 to the power ten)
..and indeed "b/B" which in most cases is taken as "bytes" (as it is in this context) but in serial communications (networks these days rather than RS232) merely "bits" - and since there are 8 bits in a byte it makes a difference* so your 10mb/s ethernet cable is 10 mega bits per second (less than 1 mega bytes per second).
*that doesn't take in account any extra bits tacked on to each byte during transmission for parity/error checking...
Sorry - drifted off there on a major tangent
}