I think I have the machine ready to go. I intend to cut 3/4 plywood most all the time. I have a skirt with a radius-ed edge all the way around the 4 X 8 cutting surface, for the sled overhang to rest on. Many of my parts will be nearly the size of a full sheet.
I also have a 12’ beam which is raised about 4 1/4", and will be using a 1/4" tool.
I intend to make one very shallow cut to verify that I am on size without wasting a sheet of material. If I am on size after the test, would you recommend I finish the part with a few cuts or cut the whole 3/4 inch at once?
I guess the question is do shallow cuts improve accuracy?
Making shallow cuts does not improve the accuracy. It is often used to check accuaracy of cuts (more like repeatability of system).
The depth of cut decision should take into account the type of bit you are using and the material toy are cutting. I experimented a lot before finding out what worked best for my needs. I finally settled on setting my cut depth based on the tabs I was using. I cut 3/4" using 3 passes of .25" as my tabs are .025 high. I would not do a single plunge for that depth without testing first on scrap material. I don’t think it would be good for you router bit.
I recommend that you play (test your machine and methids) before you try to cut your important work. I burned through 3 full sheets of low quality material getting mine tuned in and myself comfortable with the software side of the Maslow experience. I had more accuracy issues with software than the mechanical system itself.
The general rule-of-thumb is depth should equal 1/2 the router bit diameter. So 1/4-inch router bit means a depth of 1/8-inch (0.125 inch) per pass. I normally run at around 0.14-inch so I can make sure the last pass is all the way through the plywood.
That’s the general rule indeed. If you use a compression bit, you need to go deeper than the first part, otherwise you don’t use compression…
@TAD please share your experiences, one day I will make a central topic about it
When you do, include it in the wiki category
I do not have the patience for .125” or less passes, so for .75” ply, I tell the design software the material is .8” thick, and do .2” passes with .2” tabs. Play with the router speed… for me, around 12000 works well. For .5”, .54 thickness, .18 passes and tabs. If you get a burning smell, the rpm’s are too fast. Slower rpms give a little bit chunkier sawdust, less noise, and a decent cut. No matter what, some sanding is required.
Ok fellow Maslovians I’m thoroughly confused. Nobody take this personally because it is not aimed at anyone personally. I see a lot of comments about engagement of two flute bits, particularly that they don’t work properly unless most of the bit is engaged. But then, I read Bar’s post: 2 Flute Compression Bit Feeds & Speeds which indicates that they are designed to engage both up and down flutes at 1/8 inch @ 40ipm, my reading also leads me to understand that the ridgid runs too fast so the lowest setting (10K) is recommended. I have been looking at everything I can get my grubby keyboard fingers on across the interweb and have not found any concrete information to contradict this.
In my own stumbling around (tired of waiting forever on the Maslow to cut) I started using .18" @20ipm with tabs of .18. The local plywood (other than expensive birtch) is 23/32 so this allows me to use 4 passes and shaves off some serious time. However, I found at lower speeds the noise is horrendous so I ran at higher speeds which cooks bits, as I unceremoniously found out the hard way.
I even toyed with the idea of dragging the information I could verify from multiple sources into the wiki, as there is a wiki for speeds and feeds but nothing in it. https://github.com/MaslowCNC/Mechanics/wiki/S&F---Speed-and-Feeds
It would be great to get this sorted and some kind of standardized agreement on basics that would help everyone. I’m willing to help however I can if anyone else is also interested in pursuing this.
There have been a lot of threads on feeds and speeds.
At Makerfaire, Bar was running the single-flute spiral bit and it was far
noisier than the harbor freight dust collector. I had him try a 1/4" straight
single-flute bit and we found it was a lot quieter (and a slightly better cut)
when we tried a 5/8" straight single-flute bit at 48 ipm cutting all the way
through the material in one pass, it was a lot sounder (sounded horrid), but the
cut quality was pretty good.
depending on what you read, recommendations are for the depth to be from 1/2 bit
diameter to 2x bit diameter (with special cases where you are not cutting all
the way around the bit that say you can go to 3x bit diameter)
I think this bit diameter stuff is probably very questionable. When you double
the bit diameter, the area of the bit is multiplied by 4x, so a 1/2" bit is
close to 16x as strong as a 1/8" bit, so saying that it can only cut 4x as deep
on each pass doesn’t really sound right.
The depth recommendations are also written on the assumption that you are
feeding at the fast recommended rate.
Given that we are at or below the bottom of the recommended rate, I think it’s
probable that we can cut deeper than ‘recommended’
But the bottom line is that you need to try it with your bits on your material
to find out if the finish is good enough for your requirements. The book is a
place to get started, not hard limits.
Thanks David, I certainly bow to your knowledge and experience. I guess what I am driving at is there should be something in the instructions/assembly guide about feeds and speeds and a place to get started. Maybe I’m off base just a suggestion. I think I understand it now but I have gone through a lot of gyrations to get to this point.
help summarizing the various forum posts on the topic (or even just finding them
and adding links to the wiki) would be greatly appriciated.
For what its worth, my router manual just says never exceed 1/8" depth of cut per pass. Period. Nice and simple. But my patience wouldn’t last 6 passes per sheet.
So here is a formula to complicate things.
((Desired length of bit protruding through back side) + (sheet thickness)) / (Desired number of passes) = Depth per pass.
Thank you for all the advice.
I am not a very patient person and I would love to plunge a 1/4 bit through the 3/4 ply and cut everything in one pass. That said, I do not want to use several sheets of ply to get one good part.
I will cautiously proceed and when I have a good feel as to what works best for me, I will share that to this thread. If at that point, I feel knowledgeable enough, I try to help assimilate some of the data out there in one place.
Think about how you’d use the router without an attached CNC machine. We’re cutting at speeds that are more like you’d use by hand (never actually measured those, might even be slower) rather than in a zippier commercial cnc machine.
I can’t remember the last time I did a partial cut with a handheld router. I’m sure I have, especially back when handhelds were less powerful (just got my first trim router, a Rocky in a lathe fluting system, still in the box), but maybe it’s just age. We’re using bits that are for the most part used by guys (gals) holding on to the router and using an armstrong motion control system.
As they say, food for thought, whatever that means
totally agree using a router by hand will teach you a lot of intuitive things.
When I use a router by hand it is typically to make a nice edge on a long board/sheet or with a router template. in both of these uses one can easily apply 40 lbs or more force and go at least 2x if not 4x the speed of maslow.
Made some 3/4" MDF circles a while ago. did it in 3 or 4 passes with a small palm router dewal 611. Intially tried doing it in one pass, but the dust was so excessive it jammed.
If I have to knock out 40 pieces of something much faster to make a template and use a handheld than using maslow IMHO. of course with out a template, is where maslow shines
Definitely, when you need to make many of one thing, the Maslow is the template maker. The challenge as I see it, is that when holding the router you have feedback through your hands, pressure and speed can be altered on the fly. However, we are much less accurate than the Maslow with our movements. I have even gouged up some nice wood when using a template and a pattern bit. I guess the trick is finding a happy medium between speed/feed/depth compatible with the variables for the Maslow where the human can’t get the same feedback and make adjustments on the fly.