Bits, Feeds & Speeds, and Accuracy

Looking for help understanding these hot points for CNC specific to how I use the X-Carve. I’ve done a lot of reading and experimenting and I’m still not getting it.

1000mm
Dewalt 611

I cut mostly 13/16" hardwoods- Maple, Walnut and some softer hardwoods, cherry and poplar; and I usually cut either deep pockets or thru the material. Our main product that I use the X-Carve for are our nesting name puzzles. I will add some photos.

I also cut 1/4" maple MDF, pockets and thru.

I have never achieved a consistent small circle. I usually do get a good large circle. I can live with this, though it can be irritating at times.

My main issues are the inaccuracies and speed for the nesting puzzles. I use the Easel recommended feeds and speeds, because anything above that gives me inaccurate parts that require additional work to fit properly. I run the router between 1-2 and the my bits don’t overheat and the chips look good, I have run the router higher, between 2-3, but it has not seemed to make a difference. I mostly use these Amana bits.

My most recent experience is I was having bad cuts, I supposed the bit was dull. The parts weren’t fitting well and at the starting point for each object there was a bump were it seemed that deflection was making the cut off as it went around and then it realigned at the beginning and then was off again by the end. I wish I had a photo, but I don’t. The bump was perfectly consistent at every pass, so it wasn’t the motors stepping off, it always began the object at the right place, it just couldn’t make it back. So I changed the bit, did a few name plates, they looked perfect, and then the bump began to appear again. Surely the bit can’t dull that quickly.

I have not done the strengthening mods, I can, but at the speeds I’m moving surely that can’t be affecting my cuts. I had my G-Shield burn out on me recently and while speaking to customer service they suggested I tweak my potentiometers, as many of you do. I increased them precisely as much as he directed and my circles were terrible, so I moved them back down.

I have checked the square of my machine. I constantly adjust the v-wheels. I make sure that both arms of the gantry are at the same place before each cut. I always measure my bits.

So what are your thoughts. Wrong bit? Wrong speed? Wrong user?

@Earwigger @AllenMassey I’m calling you guys out 'cause you really seem to know a lot about this, but anyone else with experience with doing deep cuts in hardwoods, I love to know what your doing to make it work for you.

Here are a couple of photos of some of the stuff I do.

1 Like

The bit you are using looks perfect for what you are doing. Keeping the Dewalt RPM low like you are doing is definitely the correct thing to do. If I was doing that cut I would keep my feedrate at about 45 ipm and my doc at about .1 inch

The other thing I have learned is that when making deep profile cuts it helps if the width of the cut is about 1.25 times the diameter of the bit. This keeps the bit from binding when it is deep in the cut.

I wish I could run it at that speed. I’m usually around 30 imp at .03 doc.

The photo of the pocket cut is actually a two stage cut, first with a 1/4" then getting the smaller parts with an 1/8" bit. This was my first two stage cut and I was happy with the finish product, I just wish it didn’t take so long.

I based my RPM on the info you have posted in the forum. I killed my first router within a month running it full speed all of the time, because I didn’t have a clue that faster didn’t mean better. So running it at a lower RMP definitely gave me a lot more life out of my second (it died yesterday).

When you say it died, do you mean the brushes wore out? If so they are very cheap and easy to replace.

http://www.ereplacementparts.com/dewalt-dwp611pk-type-premium-compact-router-combo-kit-parts-c-1009_2726_180562.html

1 Like

Yeah, the brushes wore out. The first one I sent off for warranty repair as I had no idea that it was my fault (or at least it was because of the way I was using it.) I have it as a replacement ready to go because I knew that with as much as I run the router the brush life is limited. That’s a great source for parts, I didn’t consider replacing the brushes on my own. I hadn’t decided what would be ethical at this point in sending a tool off for warranty repair for an issue that I know now is really just “wear and tear.” Fixing it myself is a great solution to this moral dilemma.

1 Like

You must really be keeping your X-Carve busy! Are you in a production mode with it?

Yeah, that’s why improving the speed and accuracy is so important to me. I bought the machine, not really having a clue about CNC, late last fall to see if we could make our name puzzles with it. Before the X-Carve I was scroll sawing the letters from walnut and the bases from plywood. We sold a lot of those and they were ok, but when we added the X-Carve and began making the nesting base out of solid wood the product really became something great and we keep selling them. We now use a variety of woods and for them.

Now, just a few months later a CNC has become integral to our business. We still make some of our products by hand with the scroll saw and band saw, but we have several CNC specific products that we couldn’t make without one, and with more ideas in the pipes I want the X-Carve cutting as fast as it can.

That is a great success story! I love my X-Carve, but if I were running a business I don’t think I would want to use it as a production machine. I spend a lot of time continuously doing preventative maintenance and tuning and I still get the occasional ruined project do to a vwheel being a bit loose. For the hobby stuff I do it does not matter very much, but if I had a schedule that required me to make 100 parts a day and every screw up dug into my profit margin I don’t think I would be using an X-Carve.

Have you looked at machines like the Laguna IQ or
the Stinger

They do cost a lot more than an X-Carve ($6 to $7 k) but they can cut 3 or 4 times as fast.

I would strongly suggest the x and y axis mods. A steel plate or aluminum t between your rails and also bracing for you y axis.

That bump is probably from flexing when your bit plunges into the material. The mod is very easy to accomplish and you will be thankful later. Also, I use a much larger Hitachi router on my 1000mm machine which has more mass and horesepower and I am still on my first set of brushes after 4 years.

For cutting out your letters, try using an 1/8" bit. It will apply less force when plunging and you will get better detail. I would not be surprised if you could run it at .08 - .1" depth of cut and 30-40 ipm. Also, try to find a “downspiral” or down cutting bit. Try to find a bit that has a cutting length equal to but NOT greater than the maximum depth of cut. The less bit that sticks out the better your cut. Your letters will be much cleaner.

Also, I use V-Carve Pro so I am ample to “Ramp Plunge” into my work and create “Ramped Tabs.” Both help create more accurate shapes and easier clean up afterwards (especially with a down spiral bit). I am not sure if those features are available on Easel.

One more difference: I use a Gecko G540 driver for my steppers and Mach 3 for my cam. My steppers run at 48 volts and I can keep my machine very, very tight. With as much work as you do, you might consider more commercial software. On the Vectric website (home of v-carve pro), look at the tutorials and see if you find them appealing.

Good luck and feel free to ping me with questions.

Yeah, Allen, that’s pretty much where I am with it, I appreciate the machine as a hobby machine and an introduction to CNC, but it’s not meant for production at a high level, unless you modify it to become something else I suppose.

I have looked at some of the other introductory commercial machines and think I’m set on the Stinger I. There are several other companies that maybe make a better machine for the same price or the same machine for less, but I like that with CamMasters you know where the machine comes from, the US, you have direct access to customer service and parts, and they have a great list of add on items, so you can continue to improve the features of the machine. Some people are more into the build-your-own thing, but I want things set up and ready to go, and anything that I buy later to be a direct fit.

But that being said it’s going to be a couple of months before we make that leap. I would like to get past tax time and push out a few more products so that we know we can keep the faster machine busy and earning back the expense.

1 Like

Thanks for jumping in @Earwigger. As I told Allen, long term I’m hoping to upgrade to a more commercial machine, but I would love to get more out the X-Carve for now.

I think deflection is a definite problem and I have read through the Stiffening Mods threads a few times already. They are fraught with people trying things and offering suggestions and some people doing things and saying why it worked and how it could be better. It would be great if someone just wrapped up the thread at the end saying “this is the best way and this is how you do it.” Maybe it’s in there, and I just get lost. The other side of it for me is I’m hesitant to make a change because I can’t waste time with the machine being down. If I make an adjustment and it upsets my cuts I’m throwing money away and I’m adding to the pressure of how far behind I already am.

But I’m ready to bite the bullet and do the mods, so I will try to find the correct measurements for the thickness of the metal and get it ordered. I already bought some brackets for stiffening up the y rails and I know this will help I just hope I can get it accomplished without mishap.

It’s has been difficult to find a 1/8" bit that will cut through 13/16" material. I have one, but it’s not really for wood, and according to the Amana customer service it’s the only one the carry. Inventables offers one in a straight flute rather than spiral and maybe that’s worth trying. I would use less material and get better defined objects if I were able to use a smaller bit.

I went with an up cut spiral because it’s seemed like a good choice when cutting deep, so that the material was pulled out. With a down spiral don’t you risk heating up your bit as the material is not ejected as effectively? When my bit is sharp, I am actually really impressed with the finish. There is fraying at the top edge which increases as the bit dulls, but we round all of the edges anyways in the finishing process, so that our products are really smooth for young children, so the fraying doesn’t have much effect. We belt sand, orbital sand, and mop sand everything. It’s part of our business model and why we have done so well, our products are a pleasure to hold in your hand.

As far as software, I know I’m going to have to upgrade to V-Carve eventually, but Easel really has been a great introduction to CNC software and I have been pretty happy with it. I would have been totally lost had I started with a commercial level software (5 months ago I didn’t have a clue what tabs were, workpaths, feeds and speeds, and a whole lot more.

What kind of stuff are you cutting and how much do you run your machine?

Thanks a ton for your help.

First: YOU need to take a Sunday for experimentation. No production, no worries, just experimentation. Always set aside time to get thing right. ALSO - WRITE EVERYTHING DOWN. You will not remember what you learned. 15% or your time should be spent on maintenance and learning.

I cut everything essentially. I am a nerd with a short attention span. In October, I started selling stuff to help pay for my habit: (https://www.etsy.com/shop/ShadywoodSigns?ref=hdr_shop_menu). Recently I am into aluminum and brass.

As for what you are cutting, just order 1/8th bits on Amazon. Two flute, .75 cut depth, 1/8" shank and you will be fine. If you are finishing the top edge anyway, then up cut is fine. Once your machine is dialed it, you can use downcut or compression cut (combination) and it will be fine.

Five or so years ago, I learned on v-carve with two children under 4 and a full time job. I think it is better to learn on more capable software, especially when the tutorials are so good. The stiffening mod debate must be taken with a grain of salt. It truthfully took me less than an hour to accomplish these mods (steel plate and angle brackets). But I was not afraid to drill through aluminum and steel. AND I had clamps to hold my axis tight together when I drilled. Truthfully it is no big deal. Get everything lined up. Clamp it. Drill. Done. If you fail, replacement makerslide is CHEAP.

If you don’t have time to experiment, you are cheating yourself. And once you start experimenting, you will look forward to those opportunities like a kid looks forward to going on vacation.

2 Likes

Take Sundays! haha :joy: I work every day of the week including Sunday already, with 2 children below 4 and 2 above.

But seriously it doesn’t matter if it’s Sunday or Tuesday, if it’s got to be done I’ll do it. It just seems like a lot of these guys mess with machines, just to mess with their machines. But I’m convinced of the importance of the rigidity. It’s ridiculous how much flex is in the rails and I know just slipping a piece of plywood in between them made a difference, so bolted steel would be a world of a difference.

I have scoured Amazon many times looking for the said bit, but I’ll keep looking. I have wished I could use a smaller bit from the start.

You are right “tinkering” as my wife and I call it, when one of us sneaks time to work on a side project, is important. We have come up with a lot of great ideas from tinkering.

You have some cool stuff on your etsy page, very New England-ish :grinning:

Working with wood has been fun and the possibilities really are limitless and I love what a CNC adds to our business.

Since we’re sharing here’s our easy page

It started with my wife sewing things on the side for people a few years back then people asked her to do small wood things and then she was having to do so much that I was helping after work, and then I was taking time off from work to help her, and now it’s all we do.

1 Like

Nice store! Here is one of my favorite bits: http://www.amazon.com/gp/product/B00KZM3F1E?psc=1&redirect=true&ref_=oh_aui_search_detailpage keep in mind the cutting depth is only 1/2" It makes perfect letters and shapes the require very little finishing.

Here are some cheap, short 1/8" bits (upcut though): http://www.amazon.com/HQMaster-Carbide-Router-Acrylic-Hardwood/dp/B010NI39WO/ref=pd_sim_469_2?ie=UTF8&dpID=51omY7hddYL&dpSrc=sims&preST=AC_UL160_SR160%2C160&refRID=1GY8KN3RKZ5CTHBV918F

I’ve been having pretty good success lately with the X-Carve, keeping everything tight has made a big difference and I’ve been able to up my speeds some. I still haven’t done the rigidity mods, but I have everything to do them so–soon.

You mentioned your bigger router though. I have a project that requires a 1/2" collet so I’m considering upgrading. What router are you using and how did you mount it?

You also mentioned you haven’t burned up your brushes, how much do you actually run the router a week? Any idea? I probably run mine between 20-30 hrs.

Here is my Hitachi Router setup (but I did the rigidity mods). This now has a dust shoe and a tachometer hanging on to it as well:

It probably ran 10-12 hours per week for at least five years now. And the brushes are still very close to original shape. It’s crazy. It probably has to do with considerable horsepower and very light duty on a cnc machine. Might also be that it is a Hitachi. It is also very, very quiet at low rpms. Even quieter than my Makita on my smaller machine.

Here is a pic of the current set up:

Also - if you have V-Carve, I have a nice Dust Shoe/Air Deflector design if you upgrade to the Hitachi:

How many bolts did you use across the gantry and did you put something on the inside more than the steel?