Production Strategies For A Home Built Machine

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Production Strategies For A Home Built Machine

Postby bdring » Thu Nov 18, 2010 2:29 pm

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Ways to optimize productivity on a home build router.

http://www.buildlog.net/blog/2010/11/pr ... t-machine/
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Re: Production Strategies For A Home Built Machine

Postby Tweakie » Fri Nov 19, 2010 9:56 am

As always, a nice writeup Bart.

Tweakie.
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Re: Production Strategies For A Home Built Machine

Postby artwood_decor » Fri Nov 19, 2010 2:01 pm

I've learned many tips from your article.
You were right about fancy 3-4 flute, I couldn't resist the temptation and bought some as they were on sale, however more expensive than single flute, and they just burnt the wood, and created a lot of smoke.
I sometimes print 1:1 portions of part to be cut, especially when the part is very tight in the material I have. The print helps to locate the part and the allowable space for clamping.
The screws can be safely added in the large enough pockets that are closer to the center of the material, and cut those particular pockets as a last step. (Never used this method, the idea came when I read about cutting from the center and using wood screws)
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Re: Production Strategies For A Home Built Machine

Postby bdring » Fri Nov 19, 2010 2:19 pm

High flute count tools definitely have their place. They just don't work well for high speed spindles common on most home built routers.

If you are looking for a good app for calculating speeds and feeds...look here. He has a nice blog too....


http://www.cnccookbook.com/CCGWizard.html
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Re: Production Strategies For A Home Built Machine

Postby sansbury » Wed Apr 27, 2011 4:57 pm

1. You're doing really really well to get that long a life out of 1/16" bits. In general, you want to use the largest possible tool, as larger tool = more rigidity. Rigidity is largely a function of cross-section, which increases as a square of diameter. A 1/16 bit has a cross-section area of .003", while a 1/8" bit has .012" and a 1/4 one has .049. So the 1/8 bit is only twice as wide but 4 times as thick and consequently very roughly four times stiffer.

2. After tool diameter, the easiest way to increase stiffness is to use the shortest possible tool. If you hold a pencil at the ends you can snap it easily, hold your fingers one pencil-width apart and it's very difficult. Cutting your tool stickout length in half will get you a lot more rigidity.

3. >2 flute tools are mostly for metal, no? Even aluminum usually is done with 2 or 3 flute mills unless you're talking larger (like 1/2" or more) tools. More flutes = more rigidity but also provide less room for chip clearance. IIRC the plastic shop I work with usually uses single-flute bits on their routers. You can get these at MSC and other industrial suppliers.

4. For fixturing flat sheets, I love double-sided carpet tape, which has a sticking force of like 40 pounds per square inch. Even works on aluminum plate and sheet steel if you're careful, and is awesome for softer stuff. For sacrificial boards, masonite is cheap, and another great source of material are cutting boards from a restaurant supply company. They usually carry HDPE in a variety of sizes and thicknesses and you can usually get all kinds of material pretty cheaply.
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Re: Production Strategies For A Home Built Machine

Postby BenJackson » Wed Apr 27, 2011 8:24 pm

A flow-through vacuum table (where the vac pulls through the MDF spoil board) requires 10s of HP to work, but if you are willing to cut and gasket a job-specific table you can probably hold down your job with a fairly small vacuum pump. That's also impractical for most home users because they're not going to repeat a job in sufficient job for the setup to be worthwhile, but for "home production" it would be a good tradeoff.
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Re: Production Strategies For A Home Built Machine

Postby bdring » Thu Apr 28, 2011 12:50 pm

I just installed my new water cooled spindle. I bought it from our friends at Love Happy Shopping. It is a 2.2kW VFD based unit. It works great. My primary motivation was noise. My old Porter Cable 7518 was a real workhorse, but so freaking load. This unit is much quieter. You can actually work without ear protection on some materials. The HPDE makes almost no noise when cut.

The 7518 noise comes from all the air it uses for cooling. I think the brushes make noise too. That air also blows fine dust (and parts sometimes) around the shop. The new one makes dust collection easier. I hated cutting the MDF frame for the electronics kit. Now it is fine.

It has hundreds of options that I will probably never use, but I like the speed ramp settings. It set it to ramp up and down in 3 seconds. It is nice because it stops a lot quicker than the 7518. You can even add a braking resistor if you want it to really stop fast. I am using pot control for speed rather than Mach3 control. You can control it via modbus or voltage. That allows to to store speed settings with the tools in CAM software, but I prefer being able to tweak it right at the machine.

It only took about 2 hours to install. Most of the time was spent threading the water lines and power cable through the cable carriers. The last act for the 7518 was to cut an adapter to fit the spindle bracket.
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