Tabletop CNC

[Brian Rupnow]

This morning I'm setting here thinking about tabletop cnc routers capable of machining metal. I have been searching online, and right now I'm suffering from information overload. What has me thinking about such things?--Mainly machining cams for the engines I build. My cams are small, never more than 1" diameter overall, with bores from 3/16" up to 1/2". I use Solidworks design software, so creating .dxf files is no problem for me. I wouldn't need a large area coverage, heck, 6" square would be more than enough. It would probably have to be a 3 axis machine. My cams are first machined from 01 steel, then heat treated after they are machined. Tell me guys, do you think this is feasible? There is no way that I can justify the expense, but I might even make custom cams for other model hobbyists. I wouldn't be machining entire camshafts, just single cams with a hub and set screws similar to the picture.

 

[Brian Rupnow]

Okay, I just got back from a run across town---and I been thinkin---If I was using the machine to cut cams only, I wouldn't really need 3 axis. For the cam in the attached picture, I would turn the hub o.d. in my lathe using a 3 jaw chuck. For the bore, I would again use my lathe and put the bore in. For the reduced diameter next to the hub, I would use my lathe and three jaw chuck. For the part that is actually the cam, I would just turn the maximum diameter of the cam, again in my lathe. That way, the table would only have to move in the X and the Y ordinates to cut the cam.

 

[Ghosty]

Brian.
It may be worth it. Cam cutting is not all that easy. Also you could machine the nose radius as well.
I was looking at doing a cam grinder, but getting materials, mainly the gearing and belt systems at the time, slowed me down.
Cheers
Andrew

 

[Jasonb]

Held vertically the CNC is very good for single cams, a cam grinder is better if you want a longer solid camshaft with multiple cams on it. It is possible to loctite several individual cams onto a shaft. As said the nose radius is done as one and you get nice smooth transitions from base radius, flanks and nose radius.

I doubt you will find much with 2-axis off the shelf and it would be useful for other things to have the 3rd.

rather than use DXF can you export a .STEP file? if so use that and some free CAM software to produce the G-code, something like Fusion 360 will do.

The routers can be a bit fast for steel so you will have to limit yourself to small diameter cutters to keep a reasonable surface cutting speed maybe 5/32 or 3/16 and that is with a variable speed router turned right down using carbide cutters. also as they are not so rigid you will need to take shallow cuts.

I'd leave the cam part at the 1/2" nominal stock diameter so you can be sure the CNC cuts it all round just in case you don't clock the centre dead true and end up with a small flat on the nose.

 

[timo_gross]

Making a router just for cutting cams sounds "overkill". How about a "Toolpost mill". Milling spindle on the toolpost of the lathe . You need two axis to move the spindle up-down and in-out and keep the part stationary. Or you need one encoder on the spindle and only the cross slide moves in and out.
Something inspired by this youtube!

 

[jquevedo]

You can always look for an old EMCO F1 CNC mill, I have one milling envelope of about 4.5 x 7 inches, they are superbly built, may need some upgrade in steppers or controller based on your needs.
You may pick up one for less than 1000.00 USD
I can do 2D and 3D milling, have made some cams for Atkinson engines and Radial engines ( 9 Cylinder Hodgson) with very good results.
Hame made very niece pieces for other engines like Valve covers, intake manifolds, crankcases for small 4 cylinder flat..
You should try to find something with a square column and well built.

 

[davidyat]

Brian,
I got very lucky. A friend of mine upgraded his CNC and because I've done a lot of favors for him, he just gave me his old system and allowed me to use his Easel account. I draw 2D items in Autocad, save the file as DFX, put the file into Easel, get the g-code and cut out the parts. Because this system originally was intended for wooden signs, I have to tell the CNC program to slow way down on the passes and only go down 5 or 6 thousandths on each pass. Yeah, it takes forever but it works for me. The only thing I found that's a problem, the program cuts the parts a little smaller than what's called for. I usually have to add 10% to the dimensions to get what I want. All of what I cut, it doesn't matter that much on the dimensions, I only have to accurate where I drill the holes. I'm just putting in my 2 cents and I realize that you have to be rather accurate for what you want to do. Some pictures:

 

[ShopShoe]

Brian,

Whatever you decide, I'm sure you'll post it and I will definitely be watching.

It does seem to me that with your abilities you could really benefit more from a mill with X-Y-Z capabilities rather than a router as it would allow you to speed up the process of making many more things that your brain can come up with.

I realize that you probably need to build a budget-increasing device first (Ha-Ha), but I don't think you'd be sorry.

Best of Luck,

--ShopShoe

 

[Toymaker]

Seems like all you need is a CNC rotary table mounted onto a single axis table, also CNC controlled, mounted on mill.

 

[Jasonb]

I've got a couple of cams to make for an engine that I was that not going to be doing for a few weeks but I'll bring them forward and video it for you in the next few days Brian.

having full 3 axis would allow you to do say a pair of cams on a common hub if you used a tee slot type cutter so it can reach the lower profile and not wipe out the top profile. So you could have inlet and exhaust set to the correct angle with the grub screw boss in between them.

 

[Brian Rupnow]

All very, very interesting, fellows. I had not ever seen the video posted by Timo_Gross

 

[stanstocker]

Most routers aren't able to do good work in steel. The spindles are not up to the task in many cases, and the frames and beds aren't stiff enough. Accuracy and repeatability may not be sufficient for your desires.

These days for this scale of work I'd be looking at buying a CNC ready Taig mill and adding my own steppers. A black box controller from openbuilds or similar folks would get you the latest grbl, 4 axis of motor driver, and a 32 bit controller with limit switch, pwm or vfd control, and the all important E stop. Tis is based on cost for capability. Obviously a Haas or better yet an Okuma or a Kern 5 axis would be lovely, but few hobby folks have the funds for such wonderful toys. Not to mention power, space, and heavy enough floors.

I have a 4 axis Sherline mill set up with CNC and it works well enough, but the Taig is a much stiffer heavier machine for the same or very similar cost. There are more involved way to get there, and having 2 routers (Lead1010 and a C-Beam), 2 lasers (diode large work area and a CO2), 2 cnc mills (Sherline and G0704 conversion) , and a cnc lathe (Emco 5) in process of conversion I have done the whole linuxcnc vs mach3 vs mach4 vs gRbl thing over the last 15+ years. Taig CNC ready, a couple steppers, black box controller, and a 24V 10A switching power supply is how I'd stand up a basic works well enough system at minimal cost and with less effort than most other approaches.

CAM software is an entirely different topic, but there are free and low cost options that have post processors for most all the machine control software flavors out in the wild.

 

[ajoeiam]

Most routers aren't able to do good work in steel. The spindles are not up to the task in many cases, and the frames and beds aren't stiff enough. Accuracy and repeatability may not be sufficient for your desires.

These days for this scale of work I'd be looking at buying a CNC ready Taig mill and adding my own steppers. A black box controller from openbuilds or similar folks would get you the latest grbl, 4 axis of motor driver, and a 32 bit controller with limit switch, pwm or vfd control, and the all important E stop. Tis is based on cost for capability. Obviously a Haas or better yet an Okuma or a Kern 5 axis would be lovely, but few hobby folks have the funds for such wonderful toys. Not to mention power, space, and heavy enough floors.

I have a 4 axis Sherline mill set up with CNC and it works well enough, but the Taig is a much stiffer heavier machine for the same or very similar cost. There are more involved way to get there, and having 2 routers (Lead1010 and a C-Beam), 2 lasers (diode large work area and a CO2), 2 cnc mills (Sherline and G0704 conversion) , and a cnc lathe (Emco 5) in process of conversion I have done the whole linuxcnc vs mach3 vs mach4 vs gRbl thing over the last 15+ years. Taig CNC ready, a couple steppers, black box controller, and a 24V 10A switching power supply is how I'd stand up a basic works well enough system at minimal cost and with less effort than most other approaches.

CAM software is an entirely different topic, but there are free and low cost options that have post processors for most all the machine control software flavors out in the wild.

Mr Stan - - - you mention 4 different options for controls.
Which do you recommend and then why?
Also CAM software - - - do you have any that's linux usable?

TIA

 

[toolsrul]

This morning I'm setting here thinking about tabletop cnc routers capable of machining metal. I have been searching online, and right now I'm suffering from information overload. What has me thinking about such things?--Mainly machining cams for the engines I build. My cams are small, never more than 1" diameter overall, with bores from 3/16" up to 1/2". I use Solidworks design software, so creating .dxf files is no problem for me. I wouldn't need a large area coverage, heck, 6" square would be more than enough. It would probably have to be a 3 axis machine. My cams are first machined from 01 steel, then heat treated after they are machined. Tell me guys, do you think this is feasible? There is no way that I can justify the expense, but I might even make custom cams for other model hobbyists. I wouldn't be machining entire camshafts, just single cams with a hub and set screws similar to the picture.

Hi Brian,
I have a full 4 axis Taig with Deskcnc software with servos that can easily run a .dxf file as you mentioned. I’d be willing to work with you to narrow down a few possible stumbling blocks. If you can PM me we could work something out without boring the group.
Thanks,
George

 

[danallen]

Hi Brian,
I have a full 4 axis Taig with Deskcnc software with servos that can easily run a .dxf file as you mentioned. I’d be willing to work with you to narrow down a few possible stumbling blocks. If you can PM me we could work something out without boring the group.
Thanks,
George

Please bore the group. I am interested in this thread.

 

[ozzie46]

Please bore the group. I am interested in this thread.

Yes, please bore us.

Ron

 

[Olli-Matti]

Anyone using Taig mills in Europe? Is there a dealer somewhere around here. Got me interested in the Taig Mill as searching a suitable first desktop CNC mill has proven a challenging task. Been looking around for two years now it seems and haven't found a suitable used option. New machine market is also quite limited it seems.

 

[Brian Rupnow]

Toolsrul--- There seems to be enough interest from people following this thread that we can bore them and they'll like it. I have always had trouble machining cams. My machines are all manual, and I struggle thru and do make my own cams, but they are not masterpieces. I have been researching tabletop mills for a few days, and general opinion is that the frames are too weak or the spindle diameters are too small. I don't have the budget to buy a larger more industrial cnc machine, because I'm not selling any product. This is my hobby, so I'm not selling parts downstream and making profit on any of the parts. I am posting a drawing of what I need. It has to be 01 steel. I can do the threaded set screw holes and the heat treat myself, but it's the actual machining that gives me problems.----Brian Rupnow

 

[toolsrul]

Toolsrul--- There seems to be enough interest from people following this thread that we can bore them and they'll like it. I have always had trouble machining cams. My machines are all manual, and I struggle thru and do make my own cams, but they are not masterpieces. I have been researching tabletop mills for a few days, and general opinion is that the frames are too weak or the spindle diameters are too small. I don't have the budget to buy a larger more industrial cnc machine, because I'm not selling any product. This is my hobby, so I'm not selling parts downstream and making profit on any of the parts. I am posting a drawing of what I need. It has to be 01 steel. I can do the threaded set screw holes and the heat treat myself, but it's the actual machining that gives me problems.----Brian Rupnow

Brian,
If it wouldn’t be too much of a problem could you email me this drawing in a .dxf file. I’ll make a prototype in a different material just to verify the cam portion configuration.
Regards,
George

 

[peterl95124]

Brian, take a look at the cam grinder I made, there are also others on YouTube if you search for "model cam grinder" or "grinding",
"radial 9", "ken hurst", and "ruud oort" made grinders where the cam blank and the master-cam are on different shafts, IE different (parallel) axies
"mostlyIC" (me), put the cam blank and the master-cam on the same shaft/axis,
I got the idea from Bob Hettinger, and others, but aren't on youtube, just mine,
and IMHO is simpler and easier to make, though making a quality master cam for
this type can be a trick (but just takes patience)

I will be glad to share the plans for mine (though it might take a bit for me to tidy them up and make sure they're accurate), but you can see that its a Dumore toolpost grinder, a Sherline lathe bed, an ER-16 collet holder with a long straight 3/4" shank, a micrometer head, etc, and basic machining skills.

I don't have any direct firsthand experience with CNC, but I was a professional computer software (and sometimes hardware) engineer until I retired, and can say that people without a good background in computer software, hardware, and electronics, shouldn't be trying to make a computerized anything, I've read the sort of problems such people have on various forums, its mind-boggling. And building a computerized anything is an entire all consuming hobby in and of itself, you'll never have time to do any actual model engine building. IMHO, YMMV, VWPBL, yada, yada, yada...