Does anyone have experience using OneFinity with the standard Makita router on brass? I want to use it to create countersunk holes in 4mm thick brass. If so, What bits, feeds, step downs and speeds did you use.
Thanks
Iâm on a similar journey (still very new). There are some âlessonsâ I think Iâve learned, but if others know Iâm wrong, Iâm hoping theyâll correct me!:
- Some rules for thick brass (rods, ingots, etc) have limited application to people cutting brass sheet
â Slow RPM reduces heat that can melt a piece you intend to cut. That can harm your bit and ruin your cut. - Brass alloys differ in their machine characteristics. If you want to bend metal, you need different features than if you want to cut it. The alloy with the best reputation for machining is 360. In sheet goods, the best I can find is â260 half-hardâ
- In brass sheet (where heat builds up less) fast speeds (RPM) and low feeds (IPM) are the order. Also plan on very small depths for each cut. Iâm now using 16k for RPM and 5-10 IPM. My pass depths are 0.005 to 0.008.
- Diamond Drag bits perform well if you want an easily visible image with very little depth.
- The Amana single flute carbide cutters wonât work. A $300 experiment that failed.
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David,
Thanks so much for sharing this detailed information.
-p
When machining 4mm thick brass with OneFinity CNC machine and a standard Makita router, it is recommended to use carbide drill bits, gradually increase the feed rate and speed, control the appropriate step depth, and conduct tests beforehand for optimal machining results.Specific numerical references:Understanding the Density of Brass: Key Insights for CNC Machining - Want.net
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Iâve been recently playing with cutting, engraving brass. Lots of learning, still improving with every cut. Few bits broken too 
Go slow as suggested above. I run a bit faster, but with 1.5kW spindle.
Diamond engraving goes easy, cutting is a different story.
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Iâve had success (even with brass alloy 260) with carbide bits from Bits & Bits. I recently found brass alloy 353, which should have some of the characteristics of 360 (which I still canât find in sheets). The 353 came from âOnlineMetals.comâ in thickness of 0.063". I havenât tried working with it yet.
In the image attached here, I show a completed âDial Maskâ, which will lie beneath a âChapter Ringâ (which has numbers and marks for the minutes). This Dial Mask is 0.030" thick. The cuts in the Dial mask are:
- Engraved name and a central âstarburstâ pattern. Bits & Bits 420-HF30 (30 degree included angle) with 0.010" tip. RPM 16k, IPM 15, 0.005" pass depth, 0.015 total depth
- Perforations (leaving behind overlapping arcs). Bits & Bits 425-UP062 (1/16" O-flute Up-Cut Spiral). This bit âhogged outâ the perforations but left a 0.005" set-back. RPM 16k, IPM 15, 0.005" pass depth, total depth = material thickness plus 0.004"
- Perforations (clean-up). Bits & Bits TEF30-010 (30 degree tapered end mill, 0.010" tip). This bit finished the perimeters of the perforations and sharpened the corners. RPM 16k, IPM 10, 0.005" pass depth, total depth = material thickness plus 0.004"
Other lessons learned concern work-holding and a flat surface. This project should not only remain still for the sake of proper positions of parts, but it should be absolutely still to avoid the chatter that breaks bits. It also has to be completely flat, or shallow features (like lettering or numbers) will look different at various positions around the clock. I made a spoilboard from acetal (generic Delrin) that I bolt to the QCW using countersunk (plastic) bolts. Then I surface the acetal just before I use it. The brass is bolted to the acetal (over the bolts that hold it to the table). To secure the brass I use more plastic bolts in holes threaded into the acetal). There are four bolts outside the finished area and one in the center. After the center hole and âstarburstâ are cut, that (5th) bolt is added.
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Wow. You certainly did some homework on that setup.
Any chance we can see a picture of your work holding fixture? I kindasorta get it from the description, but not fully.
Attached are two items. The photo shows the (recently used) acetal spoilboard. Itâs 6" x 12", to accommodate two Dial Masks. The four bolts that secure it to the QCW are in place with heads below the surface. There are five bolts that hold the brass down to the acetal, and four of them are loosely in their places on the right half of the board. The fifth goes in the center and is added after the central carving is done. For this project, I make the X,Y origin at the center. That ensures I can clamp the outer edges without risk of hitting them with a bit.
The second item is the VCarve file I use to make these. Itâs much bigger than this spoilboard because I use parts of it to make various sizes. To see all of its toolpaths, go through the layers.
- âFixed Itemsâ refers to the tracks in the QCW.
- âHold Downsâ refers to through holes that center on those QCW tracks. These bolts keep the acetal in place on the QCW. Within the toolpaths you can see that these holes are also counter-sunk, so the bolt heads are lower than the surfacing bit (and the brass).
- âLayer 2â simply lays out where hole in the brass wonât interfere with the project. I drilled those as through holes and used (metal) threaded inserts on the back to accept those five bolts. I later learned that acetal can, itself, accept threads, which will eliminate metal in my future spoilboards.
Spoilboard. with inserts, large.crv (1.0 MB)
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