This has been a blast but such a rabbit hole. I recently completed my first frame, simple hardtail. After a day of bike park laps (not on this frame) we decided to see if we could break it. We were successful in breaking the chainstay in the poarking lot being idiots. Even after some good advice from the professionals here on how hard 3d printed ss pieces are to braze that was where the failure happened.
Anyways long story and off topic. I’m quickly realizing that if I want to keep doing this I will need a way to manufacture parts. Im thinking small parts like linkage sleeves for pressfit bearings and stuff like this. I was about to pull the trigger on a small Grizzly combo mill, lathe, drill but then watched a few videos on small desktop cnc machines.
Anyone have advice on which of these would be more beneficial and any recommendations on particular machines?
Honestly today the best approach might be 3D printing prototypes and ordering machined parts online to be sent to you. This is slower but I think it’s the cheapest route.
My CNC mill is a Langmuir MR-1 and it rips through steel reasonably well, but the $7k that you’d spend on one can buy a lot of internet machined metal.
We’re also in a weird time when SendCutSend charges less for most materials after cutting them than OnlineMetals or other sources sell raw material for.
It really depends on how far down that rabbit hole you want to go. I have a decent manual lathe and a bridgeport clone mill and they definitely are neccessary to do what I do. I am using 3D printed parts and just manually machine the bearing seats. I am talking to the manufacturer about getting them to machine the BB threads in and I just chase them with my hand cutter when they come in. Things like pivot hardware I make myself now but really don’t enjoy the tedious nature of the work and will be using either a bigger brands bolt kit or getting everything CNC made for me in small batches.
Interested to know what actually broke and what the failure mode was ie. complete break or a crack that grew after each load cycle and whether it was in the material or the boundary between the two parts.
I agree with sendcutsend. I need to utilize them more. I am a perpetual tinkerer and I know having one of these machines would be useful for hikes but also useful for just other crap in life. I just finished designing my linkage attachments and bought the pipe from online metals and bearings from another bike. I know I can buy from Paragon but could be fun to mill dropouts and such.
Basically I didn’t get a good braze on the joint between the 3d yoke and the cs. The yoke popped right out. Rookie mistake but the whole point was to see if we could break some part of it. Next time I will take the advice given and clean clean clean when using 3d prints.
I get it. I like having my CNC machine too, even if it sits idle much of the time.
If you have a garage or other easy access shop space and are good at tinkering (mechanically, software, and electronics basics) then I would keep an eye on the used market and pick up the first decent CNC machine in your target size range and with a decent spindle speed (8k RPM minimum). Old CNC machines have low value commercially, but are great for small workshops. Going with this route you can get something with a tool changer and that will hold up for years in a small workshop and probably spend $5-10k. As an example @hahn_rossman’s shop has a small Chevalier that cost less than my MR-1 (details below) and which fits into a similar sized space. It has a tool changer and is likely more rigid and was designed for commercial instead of hobbyist use.
If you need something that goes into a basement shop or want to buy new then these are the options that I’m aware of:
Taig CNC – I had one of these for about 10 years. It works pretty well for aluminum, but is underbuilt for steel. I used it to make dropouts, but it was really pushing the machine hard.
Shariff DMC – I’ve never seen one of these in person. It looks a little beefier than the Taig, but is much less mature as a platform and reviews that I’ve seen seem mixed. However it might be the most capable design in under $5k and at ~200lbs. If I got one I would run it with fogless mist coolant (aka MQL aka fogbuster). These machines are small, but would be able to make dropouts or probably a yoke.
Langmuir MR-1 – These handle steel easily but are large machines, requiring a roughly 4’x4’ footprint. They are sold as a kit and end up around $7-$8k after shipping and basic tooling. The nice thing about the kit is that no component weighs over 100lbs, so you can move it into a basement or other limited access shop space. However to build the kit you pour 450lbs of concrete (for dampening) which makes it a one way trip. I have one of these machines and have done many modifications (like a higher speed/tool changing spindle) to make it what I really wanted, but I also have about $10k into the machine.
The other option is to convert a benchtop manual mill (Grizzly G0704 is a popular one), but in my mind that turns into a never ending project that doesn’t get you as good of a solution as something designed for CNC from the ground up.
For home shops (where the machine does sit idle for long periods of time) I’m a big fan of MQL/fogbuster type coolant setups instead of flood coolant. Flood coolant needs to be used frequently to avoid going rancid, and old flood coolant makes everything on the machine sticky. MQL leaves no residue and chips vacuum up easily. With a narrow/high velocity nozzle MQL still does a great job of chip evacuation, you just need to pay more attention to aiming it than with flood coolant.
I have a small lathe (Emco Compact 10 – I’d highly recommend this or the Super 11 as being the rare benchtop lathe with big spindle through holes useful for framebuilders) and a small manual mill (Emco FB-1, similar to a Grizzly G0704) too. If I only had two tools it would be the lathe and CNC. If I only had one tool it would be the lathe, but I wouldn’t be making dropouts.
The two Emco machines are nice because I can move them in and out of the shop with 2 people. They are capable without being too heavy.
This is the best response ever. So much to learn. Like I said I am the eternal tinkerer. Have a full custom woodshop and weld shop and I even though I don’t know what I would use a mill for right now I’m sure it would get a lot of use over the years.
For instance I am working on designing a main linkage for a single pivot. My plan (without any milling capabilities) is a main cross link mitered into the ST, the ID of this would match the ID of the bearing. I was thinking an inner tube brazed in that would act as the bearing stop. On the swingarm there would be a tube with a flanged bushing. This is extremely hard to source with no machining capabilities.
You mentioned the G0704. I looked that up and looks great, I was more leaning toward the G9729 to have lathe capabilities for reaming out tubes and such. I have zero machining experience or knowledge so have no clue which style of these would be more suited for my needs. If you have advice I’m all ears!
If I had to do it all over again I would take a intro to machining class at the local tech college, or maybe universities with a physics department have a instrument making class.
This will get you acquainted with the he tools and how to use them. And measuring! Then I would buy a good 3d printer to iterate my parts for fit with the rest of the things I was making.
And then I would order parts from a local job shop, or online vendor depending on where I was living.
The amount of money and space that having a decent machine shop requires is no joke.
Then again it’s a delight!
Hahn’s suggestion is really good. A little seat time can tell you how you feel about precision metalworking before jumping in the surprisingly deep end. Metalworking is an extreme case of something to only take up if you enjoy the process and can say damn the time and expense.
CNC millwork is four of those - metalworking, CNC, CAD, and design for manufacture. If you don’t love spending all day on any one of those, well, surely there’s a reason most of the hobby size machines I see on Craigslist are CNC conversions.
If you already have the reamers and a drill press with enough clearance that you can rig up for low RPM, you can ream under power with a bit of clever workholding. Rogue Fab sells a quite affordable 4:1 reduction kit. It’s not as rigid as it could be but it is quite affordable.
A lathe is what you’d use if you wanted to bore or turn arbitrary precision arbitrary diameters or tapers. A mill is mainly for X-Y relative work, and can do a little boring and turning with a boring head. With tools like this you could make that reamer to use in the drill press. Most likely more expensive and not as good as a retail reamer, but some of us think that’s fun.