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[4]

My round column RF30 mill to CNC conversion, the cheap way

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stioc

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#1
So almost exactly 1yr after the purchase of the mill I've decided to convert it to CNC.

Let me get some things out of the way first, this is going to be a cheap build. Yes in a perfect world I'd have a Tormach 1100 but that would be an overkill for how much I'll use it. Nope, not even going to convert it to ballscrews, at least not yet.

Goals: cheap, quick and easy :p

Hopefully, this conversion will help someone out who has wanted to do this but wasn't sure about it, didn't know how, or thought it was too expensive. If it all blows up, it'll at least provide some entertainment! :lol_hitti

How the mill sits today:

39848675704_45d6d2cc58_o.jpg
 

stioc

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#2
My CNC experience: until about 2 months ago I knew almost nothing about CNC. Then I decided to build a small Arduino+GRBL based CNC router/engraver for knowledge and fun. This went better than expected, while I have a degree in computer engineering and did a lot of PLC and microcontroller projects back in college anyone can do this stuff these days with the help of Youtube and just general info available on the Internet. In fact, too much info so you have to weed through it all to find what you're looking for sometimes.

I had a budget of $300 for the router and I came just under it by a couple of bucks. It would've been cheaper if I didn't waste $30 or so on crappy endmills from Amazon based on their good reviews. However, the endmills from ebay seller drillman1 totally changed the tiny router from being nothing but an engraver to actually being able to cut mdf and HDPE.

Bench testing the electronics of my last CNC project
39848484704_b43598d1e1_o.jpg

Done - took about 6-7hrs to assemble it from scratch
38748885380_788100476d_o.jpg

An example of what I made with it:
38748885540_b1861df0e0_o.jpg

My biggest hurdle with CNC is not being good at Fusion360 or CAD/CAM in general but I manage to stumble through it once I have a design/idea in mind.

Anyway, this was/is my entire CNC knowledge but while the router is fun I want to be able to tackle bigger sized projects. Its working capacity is only about 8"x11" and the spindle is pretty weak. Sure I can upgrade, modify to suit my needs, I was even considering buying a Shapeoko XL but then I thought, I already have a 750lbs mill with a decent sized table why not convert that to CNC?
 
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stioc

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#3
So here's the breakdown of the electronics that I'll be using.

CNC software: While I enjoyed the simplicity and speed of GRBL running on Arduino (2 sec from boot up to being ready!) for the little router, for the mill though I wanted something with more features even if I don't have a use for most of them at this time. I boiled my options down to either Mach3 or LinuxCNC. I've chosen the latter for now. Cost: $0

Computer: I have an old Athlon X2 desktop sitting around in the garage, I'll start with it and see if I need to upgrade to something better. It's not the fastest of desktops made even back then lol. Cost $0

Stepper motors: Three Nema 23, 270 Oz from Amazon. Cost $98 total

Drivers: Three TB6600 clones from Amazon. Cost $45

Parallel port interface/Breakout board: 5 axis generic BoB from Amazon, comes with cables: Cost $17

Power supply: 400W 36V PSU from Amazon. Cost $36

Total cost for all electronics: $196
 
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FOMOGO

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#4
Cheap is good, as long as it gets you where you want to go. This should be interesting, I'll be following along. Mike
 

Holescreek

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#5
I converted an RF30 many years ago as cheaply as possible - sort of. Even after making the mounts and brackets myself I had $1k in it. Nema 23's are going to need som good gear reduction to work IMO, especially with original acme screws.

I used ball screws driven 1:1 with nema 40 500 ozin motors X&Y, geco drives, and homemade 72vdc power supply. IIRC the first 3 geckos ate up $600 of the cost. I added a 4th axis later on.
 
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stioc

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#6
Thanks guys. I'm doing this not just in a cheap way but also quick and easy way, hopefully, stay tuned! Also, I'm all ears for any words of wisdom along the way.

@Holescreek, that sounds like a great setup, I'd love to see pics as well as more info on it. The prices have come down quite a bit lately and my electronics are cheap and generic unlike your Geckos :p Yes, the motors will have gear reduction :)
 

Boswell

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#7
stioc,
This will be a great build log. I see post from time to time of people trying to understand how to get into CNC with the least cash outlay so this build might help a lot of people. Not only for how to do it simply but also after you get it built to be able to talk about what trade-offs and limitations you encounter.
 

stioc

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#8
@Boswell - thanks, the idea was to learn and share with others and if nothing else set an example of 'how not to do a CNC conversion' :p
 

stioc

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#9
LinuxCNC setup:
I installed LinuxCNC 2.7 on the old HP desktop. It was pretty straight-forward, I chose the lazy way and downloaded the full version that's self contained, meaning it'll install Linux and LinuxCNC altogether on a bare disk/computer. I did have to build a bootable USB drive - which is easily done using Rufus (Google for it) on my Windows laptop.

LinuxCNC isn't as intuitive as Mach3 for the uninitiated so I'll give a couple of pointers below. A quick background story on Mach3 first- I was really considering Mach3 but for the first time in my life i got banned on a msg board...I guess for asking questions (perhaps too many?) about backlash compensation. Their Administrator quietly banned me, funny thing is he only banned one of my IP addresses so I can use an open proxy and still cruise around and even post if I wanted to since my account is still active. However, I realized if that's their mode and attitude for providing support I should look elsewhere. I know this is probably atypical as Mach3 is used by so many people but I'm a principles guy so...onward and upward for me.

So after I first installed LinuxCNC and logged into the system I couldn't figure out where to start, I ended up in the main panel in demo mode and got frustrated pretty quickly. Then some RTFM later you're supposed to start with the Stepconf Wizard where you fill out some basic information about your mill i.e. axis config, speed, parallel port pin setup etc. When you finish it creates the initial config files etc and places a shortcut to launch LinuxCNC with those settings.

The pic below isn't my actual settings, I'll be playing around some with the numbers and post the config at some later point once I've finalized them. The default velocity and acceleration settings are on the high side in my opinion so I'll be dropping those down quite a bit to start with. Probably 1in/s for Velocity and 5 in/s/s (second squared).

40559229511_b4fe8e0524_o.jpg
 

stioc

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#10
Bench test and file transfers from Windows to Linux:
OK, so I got quite a bit done today...

I configured LinuxCNC enough to do a quick bench test to make sure the parallel interface/BoB, the drivers and the motors worked. It was a successful test and no smoke so that means I got the connections setup right lol The key is to remember not to mix up the polarity or the smoke will happen.

The wiring is messy but it'll all get cleaned up soon.
25688582517_f055ca9547_b.jpg

The drivers can microstep to something like 64k steps per revolution but I only opted for 800 steps per rev. This is to ensure as much torque as possible while still getting a decent resolution.

Oh I also got setup to do file transfers from my main workstation in the house to the LinuxCNC computer in the garage over wifi. I'm using sFTP via Filezilla which makes it drag-and-drop simple from left to right.

39700471325_dff620eafa_b.jpg

Next I'll talk about the mechanical parts...
 

stioc

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#11
The mechanical parts

OK, so far everything was really straight forward: simple, inexpensive and readily available. However, the mechanical parts was a bit of a challenge for me. I really didn't feel like building parts myself unless I had no other choice. Remember from post #1 of this thread:

Goals: cheap, quick and easy.

I briefly looked at Grizzly's kit and I mean...briefly- as soon as I saw the $5k price tag I closed the browser window :eek:. Then I found FlashCut, at the time I didn't know it's their kit Grizzly sells so I emailed them asking if they'll sell the mechanical parts to me. I got no response :boxed in:

At this point it was looking like if I wanted it cheap, it wouldn't be quick because I'd have to take the project on myself. I was coming to terms with this when I came across someone's kit by the name of PaulCNC - I saw the youtube video, then found the pricing online and thought the price was right up my alley. However, I wasn't sold on the design, it just looked too simplistic to me and I wasn't convinced it would work effectively. I'm not a mechanical engineer so when I build mechanical things I often tend to over-engineer things and make them more complex than they need to be perhaps. Anyway, I reached out to Paul via email asking for availability of the mechanical kit. As of this writing Paul sells a complete kit all put together for you to just plug in for $820. He also sell the complete DIY kit for $620 and the mechanical kit for $320 (he loves $20 I see). BTW, Paul's kit is geared towards Mach3 which doesn't matter much to me since it's the same interface as LinuxCNC just different control software.

http://paulcnc.ipower.com/site/

I asked Paul for a reference of a customer whom I can talk to about their experience and longevity of the kit. Paul sent me a contact- this gentleman happens to have a really informative website about all sorts of machining stuff. From his website I gleaned quite a bit of info already and realized he bought Paul's kit several years ago and has since made lots of things on it.
Anyway, I reached out to the contact and as suspected got a very positive feedback. OK Paul, here's my $320 via paypal...and two days later the kit was in my mailbox:

40516563992_2b69b32d16_b.jpg

The kit allows you to use the handwheels too, this was important to me as I didn't want to lose that capability if I could help it. I could see times when I'd prefer to run a job manually (e.g. repair work on say a...cylinder head, I know mighty ambitious of an example, but hey...).
 
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stioc

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#12
Mechanical parts fitting and a couple of oops:

So the mechanical parts in theory should be a matter of replacing the handles with these parts. That is if you're not me lol, for me it's not a project without some oddball issue cropping up or me messing things up. In this case it was both.

OOPS #1, looks like the hand me down mill was previously 'modified' in that the Y-axis shaft collar doesn't have 3 jaws like the X-axis...so Paul's collar can't mate with the jaws of the leadscrew collar.

The way the Y axis should've been (this is my x-axis):
39908061014_f369c0d747_b.jpg

My Y-axis leadscrew collar:
39722744275_b31fec5fa1_b.jpg

I decided to drill and tap Paul's collar and use set screws, similar to the hand-wheel that was on it. My table-top Craftsman drill-press has too much run-out for precise holes so I moved its small X/Y vise to the mill, since I'd removed the mill's handles and didn't feel like putting them on.

38748885610_04424c9984_b.jpg

Done, two set-screws in place, the other is opposite to the one in the pic.

39722744325_590c426dcc_z.jpg

OOPS #2, (self inflicted of course) when you order the kit from Paul you have to measure a few things to get the correct kit. This is due to the fact there have been man RF30 clones sold over the past few decades and there are slight variations of the shaft size etc. Well when I measured my Z axis shaft I thought it was a 1/2" dia. but it was more like 13mm so when I put it on it was *very* snug, while not realizing the issue I gave it a few taps with a soft hammer to get it about half way onto the shaft. Then when I went to remove it by tapping it back out it wouldn't even budge :confused: Well it doesn't know who its dealing with so I break out my slide hammer :scared: a few gentle taps and I see it moving...wait, its not the collar moving but the whole shaft is coming out of the housing :lol_hitti I quickly tapped it back in hoping I didn't mess up anything inside (I didn't even know what the inside looks like as I've never messed with any internals of a mill, ever.). After some head scratching and cursing I decided to take the housing apart. Luckily nothing was visibly damaged :bowdown:

39908060974_e942dca24e_b.jpg

I clamped it in a vise, then used a vise-grip as a stop for the shaft sliding out of its housing but this collar was not coming off! I ran through a couple of options in my head, slice the collar to get it off and reorder it from Paul and thought this might be my last resort. Then I thought, it's aluminum on steel, I should be able to heat it up with my propane torch and that should help. Boy, did that help, let me tell you just 1min of heat and the thing slid right off! Then I put everything back together the way it was before. At least I put some synthetic grease on the gears.

39908060984_a46fa9a693_b.jpg

Finally, I chucked up the collar on my 9x20 lathe and faced off the end and bored out the hole a few thous for a good fit.

39908060954_d91dda266f_z.jpg

Lesson learned: a bigger hammer is not always the best solution
 

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stioc

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#13
Back to the electronics
I only had about 5hrs of shop time but most of the control side wiring, layout and control board is done now, yay! I didn't even have to go to Home Depot, everything I needed I found in the garage, or put another way, I used what I had lol

I got the these cables with the breakout board, I cut one end of the connector to wire up the drivers. This made for very nice and clean looking wiring.

40561505602_57b0e99cbd.jpg


I then added power/ground by daisy chaining it to keep the wiring as clean as possible.

39926042554_a59450b2e1.jpg

Finally, decided on a layout that I liked and one that wouldn't stress the parallel port and USB cable, marked out some holes...

40561505622_a7aaff5c3b.jpg

...and it's all done! :)

40561505562_820823ab5a_o.jpg
 

stioc

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#15
It's ALIVE!!!

I got all the wiring completed and the control panel mounted.

39926042624_86cccb827b_z.jpg

39926042634_5e85714952_z.jpg

Then I dialed in the backlash using the Touch DRO...the 1.000 on the DRO screen represents the 1" jog command on LinuxCNC for each access - and they match up perfectly! In all honesty I would've been happy with a .002 error too since this is just backlash (and not the full screw mapping, which I don't know how to do yet).

39964301344_ac95d6ea82_z.jpg

My backlash settings/config, I'm still playing around with some of these settings so if anyone has any thoughts/advice I'm all ears:
26802706048_be39bf5da6_z.jpg

...and finally its first test under CNC power...using a pencil:
26802706138_9d76b17be6_z.jpg

OOPS #2.1:
There's a problem, of course...remember when I had to bore out the Z axis coupler? Apparently I didn't indicate the part properly so when the shaft spins the whole motor/assembly started wobbling round and round, son of a...

OK so what now? I could give Paul a call and buy another coupler which he sells separately on his website. Then I thought, dummy at least try to fix your mess and learn to do things properly...a learning opportunity you see? So I chuck up the collar in the lathe, indicate it to within .001" this time and bore it out to a bigger size 0.70". Then I take a scrap piece, bore that out to 1/2" and then turn it down to 0.685".

26802706198_606fc0918b_z.jpg

26802706268_b80b71dfb8_z.jpg

26802706368_47c4fbd971_z.jpg

Then I cut out the appropriate length and pressed it into the collar, took a bit of an effort, which is what i wanted. Finally, drilled and tapped a hole. The whole thing now turns perfectly!

26802706588_da736e5f9c_z.jpg

26802705998_ee6e5632e8_z.jpg

I now declare my conversion complete.

Total cost: $516 (btw, Paul sells his kit for only a $100 more than this and I would've gone that route had I not already bought some of the stuff before finding Paul's website. Also for $820 he sells a turn-key bolt-on kit which if you consider the amount of time involved in wiring is a fantastic deal.)
Total time: about 3 full days given a couple of issues I ran into
Difficulty factor: hard to quantify this but I'd say if you already use things like mills, welders, automotive stuff then probably a 2 out of 5 (5 being the hardest).

Not bad for a hobby machine, I couldn't be more pleased :)

Now Fusion 360, that's a solid 5 for me, and I'm an IT guy- I'm just not good at drawing/CAD etc. I made a design for engraving in Fusion 360 but couldn't quite get it to work right, some letters it wants to deep engrave while the others it barely touches. I think it has to do with it trying to be too smart about how wide the engraving bit is. I'm going to try the Trace function instead.

LinuxCNC also has a learning curve...I've just barely scratched the surface on it.
 
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stioc

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#17
Thanks Boswell. It was a fun and easy project and hopefully the documentation will give others a cheap way to CNC these inexpensive mills, afterall most people that buy these mills wouldn't want to spend $5k (or even $2k) on a $1500 mill. Also, the round column mills are written off but I really like mine. I used to have a mini mill and there's just no comparison, this thing weighs about 800lbs, very rigid in comparison and not much more money either.
 

agfrvf

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#18
I plan on doing something similar to my 2.5ton horizontal using a makerbase and some 50Nm steppers.
 

gzoerner

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#19
stioc,

Many thanks for your write up. You've inspired me to build a 3-axis router project. I'm just finishing my first arduino/stepper motor project for my 9x20 lathe.
Glen
 

stioc

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#21
I plan on doing something similar to my 2.5ton horizontal using a makerbase and some 50Nm steppers.
Awesome! pls post a link here when you do.

stioc,
Many thanks for your write up. You've inspired me to build a 3-axis router project. I'm just finishing my first arduino/stepper motor project for my 9x20 lathe.
Glen
That's fantastic, glad to share- do you have a thread or pics somewhere? I have a 9x20 that could become my next cnc victim lol

$516 has to be some sort of record.

Very resourceful
Thanks Paul, I'll be honest I can't take a lot of credit here because I couldn't have done it for this cheap or this quickly and easily without your kit. Thanks for all the tech-support too after I ran into my self-inflicted issues. I hope you post more on the forums such as this because I feel you have so many cool ideas and things to share especially with your Mech Eng. background.
 

stioc

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#22
OK I decided to make something on the newly converted CNC mill. It's a carriage stop for my lathe, the idea is to be able to attach it to the ways where it's fully movable along that axis. I started by taking some physical measurements of the ways profile, then sketched it out in Fusion360, extruded it to 3D, then generated the toolpath. I'm kinda getting the hang of this. For the toolpath I could've done contour and it would've been much faster but I decided to do a pocket because I really wanted to see how that comes out and the machining time of 54 mins would stress everything enough for me to have a good idea of what the machine is capable of.

I tried a shallow cut on wood first...broke the first 1/8" expensive endmill because I forgot to turn the motor on before I hit 'play', by the time I realized the damage was done, what an idiot! :lol_hitti

After swapping it out for another one I started the program again. This time the feeds and speeds that F360 picked were too aggressive and the second bit also bit the dust. Ugh, it's going to be a lot of expensive trial and error I guess :eek:

Third attempt, I set all the feeds and speeds to 5in/min and depth to .03in per pass :dunno: It worked...well until I accidentally hit the ESC key on the keyboard, which is basically ESTOP...awesome! :willy_nil

Fourth attempt, this one worked, but I had to pause it because at one point the chip brush fibers got caught in the bit as I was trying to clear the chips...I won't be doing that again. Luckily I was able to resume it where I left off. Although the dimensions came out just a bit more loose so I wonder if that was the reason.

Anyway...here it is all done, my very first metal cut on the mill since the CNC conversion. Pretty exciting for me :p.

40697729672_86c62599f3.jpg

My fancy plywood sub-plate :lol:
40030261374_f527f79a87.jpg

That mark to the left is from the second broken bit
40740424671_b6f5c18239.jpg

I'm using an old drill-bit as the stop since I didn't have a 3/8" rod handy.

38930155740_4c3c345a7e_z.jpg

40740425521_4f09f089ee.jpg
 

magicniner

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#26
I was really considering Mach3 but for the first time in my life i got banned on a msg board...I guess for asking questions (perhaps too many?) about backlash compensation. Their Administrator quietly banned me, funny thing is he only banned one of my IP addresses so I can use an open proxy and still cruise around and even post if I wanted to since my account is still active.
I've been on there for 4+ years and if they ban you they do it at account level and you don't get to log in from anywhere, if they blocked your IP it's for something else, sometimes people lose access when problematic addresses are blocked such as when an attack uses a spoofed IP address.
There's a long and funny story about a man who's lawn mower died and was reluctant to ask his neighbour if he could borrow his, the tale boils down to not telling someone to shove something until you've actually asked for it first ;-)
 

stioc

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#27
I'm pretty sure it wasn't done at the account level because that would be visibile to everyone else on the thread that the user was banned. If you do it at the IP level then it's under the covers. Anyway, lots of people I know have had good luck with Mach3 and all I say is good for them but while there's a bit of a learning curve to LinuxCNC I find it far superior and customizable for the price. In the end it all worked out for the better for me.
 

HBilly1022

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#28
WOW!!!! You certainly achieved your goals of; easy, fast and cheap. Very nice work and thanks for posting.
 

stioc

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#29
I'm getting better at F360, I used to get very frustrated with it, I can now do the basic stuff pretty quickly from CAD to CAM so that's encouraging. I loaded my 5 most used tools into the TTS collet chucks created a tool library in F360 as well as in LinuxCNC.



This height gauge had about 8thou error in repeatability due to a wobbly base, after sanding it I got it down to 1.5thou.


I then realized I needed a collet rack. No worries, let's design it in F360 real quick and let's test the tool changes for the first time on a real part so this will be a single gcode file with different operations and different tools. I also want the endmill to plunge where the center drill drilled the holes. So far so good.



Now, let's go cut it...well, except I don't have any suitable stock material. Wait, I have this set of 1/8" aluminum toe alignment-setting plates left over from my racing days back in the early 2000s...time to sacrifice, err recycle them. So I rough cut one with the plasma. Mounted it on a 1/4" plywood spoil board (I really need a better spoil board), said a prayer or two and hit the go button :bowdown:

The machine asked for Tool 4, the center drill, popped it in, it set the correct offsets and made perfect starting holes. It then moved back up to z0 and asked for the next tool (the roughing end mill), popped it in and hit ok...it read the correct offsets and started plunging. Pretty quickly though I realized something was wrong because it plunged hard and black dust came out of the hole. Oh crap, that's the mill table it's roughing out! crap!!! I hit the Esc key, manually jogged the z axis up...yep, I definitely milled my mill! :eek: But how? wrong tool offset? nope. Ah, what a dummy! I input -0.7" in for stock bottom in CAM instead of -0.07...that's going to leave a mark!



After that it was all good, actually just about perfect how it all worked out. The engraving toolpath however, left me a little unhappy because it was trying to draw these tiny hair-lines that don't show up in the design, it was mostly cutting air (almost like trying to engrave a 3D part) so it was wasting time. I'll have to look into it a bit more or try to find a better way to engrave. Which btw I used a 1/16th carbide ball endmill for (running at 4 ipm at .005" DOC). Engraving toolpath did require that I classify it as a chamfer bit (i used 60deg so it doesn't try to plunge into the valleys) or else it wouldn't generate the toolpath. I really need to find single line text fonts for these simple engraving needs.



I spent pretty much all day in the garage cutting out this part, something i could've ordered for $20 on ebay I'm sure with a single mouse click but it was satisfying to see it come out as I'd envisioned it.

 

kvt

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#30
stoic Question, How are you keeping the head in line if you have to raise/lower it. That has been one of things I was wandering about. I have a RF30, It seems like shallow stuff is ok, But if I was to work on something requiring more depth, or longer tooling could be a problem.
 
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