Considering a Desktop and have some questions

[Ross Leidy]

Hi folks,

This is my first post here after a few days of poking around the forum and doing general research on ShopBot products. I'm very seriously considering my first CNC machine purchase, and ShopBot seems to be the obvious choice based on product quality, customer feedback, and level of support. Being a complete CNC newbie, I have some questions about the suitability of CNC for some of what I'd like to do. I'm hoping the members here can help provide me with some answers. Given my application and space limitations (and budget), I'm considering the ShopBot Desktop model.

I run a side business building custom table tennis paddles, so all of the questions/comments below are related to cutting wood. I currently use mdf paddle templates and a table-mounted router and pattern bit to cut out each paddle. It works and gives me repeatability, but I do have two primary issues:
1. Paddle/handle shapes vary, and for each combination I need to create a new mdf template. I wouldn't be surprised if I have 40-50 templates I have to keep track of and store, and that number is growning. I wouldn't mind eliminating the mdf templates and the time it takes to create them.
2. Regardless of the type of trim bit I use (straight, shear, spiral), router speed, or feed rate, I do usually end up with some tear-out along the edge. Nothing really bad, but it's something I like to eliminate if I can.

So, one of the main expectations I have is that CNC will address both of these issue. Obviously, I'll need to climb the learning curve for the software/hardware before I'll see any time savings, but given that this application is fairly simple, my hope is that it won't take too long. Regarding #2, my expecation is that the appropriate feed rate and multiple passes will eliminate tear-out. Are these reasonable expectations?

I've had a number of request for an engraved personalizations as well as my own desire to place a serial number on each paddle. This is another big consideration for me in deciding whether or not to take the CNC plunge. My concern is about how small the text can be with CNC and still look crisp and uniform. Ideally, I would like to have characters about 1/8" in height (3mm or so). Can this be accomplished? It would be fantastic if some of you could post some photos here of examples of small text cut into wood. If it matters, I am considering the spindle option on the Desktop model (more for the reduced noise over the router, although I imagine its precision would be a plus for small text).

I also have some questions related to the included software. I do plan to download the eval version of VCarve Pro to get familiar with it, but I thought I'd go ahead and throw out some questions. I couldn't find any reference manual posted at the Vectric site, or I would have checked there first. Most of the paddles I design are symmetric, and I currently design the shape with Photoshop creating the left half of the shape, and then reflect the curve to get the full shape. Photoshop isn't the ideal app for doing this, but I had it so I made it work. I'm assuming that VCarve Pro (rebranded as PartWorks, I understand) has similar functionality?

While I don't expect to jump right into this next task, at some point I would like to use CNC to shape the handle grips, too. As with the paddle itself, I currently use mdf templates to cut and shape the handle grips. This would involve 3D modelling of the handle grips. Would the bundled software handle (no pun intended) 3D or would that require a different software package?

Thanks in advance for your help.

[myxpykalix]

Some random thoughts...
First you will be able to pack your templates up in a box and never use them again.
Once you create the general shapes of your paddles in 2d, and we can show you how to take a picture of your existing template and get your outside shape and turn that into a 2d vector toolpath....SIMPLE!
you would then simply load that shape into whatever pgm you choose to buy and cut that shape out of your material. That might take all of 5 minutes.

Because i don't know your product i'll assume you might apply grips much like pistol grips on a gun. One of the great things you will be able to offer is custom carved grips. Do a google search for "custom carved pistol grips". You will find the thousands of different designs for inspiration. This isn't simple 2d carving of a name but beautiful 3d carvings that would add another line of products for you to sell and a service to make money on.

I know you're thinking "I can't make 3d files!"...well you can buy them premade from www.vectorart3d.com and other sources till you can learn to do it yourself.

You can eliminate tear out will the proper feeds and speeds and bit combinations. No problem.
I have heard of guys using 1/16th" and 3/32" bits so you should be able to do small lettering fairly easy.

If you were going to do custom carved handles that you create yourself you would need a 3d program capable of doing the 3d work.

However if you just wanted to create toolapths for a file you bought say from vector arts, well they have their own free toolpath pgm.
You could also pay someone to create custom grips for you until you got proficient to do it yourself.

Realistically with some watching of tutorials, download the demo's so that when your machine comes you could be proficient enough to be cutting your first day.

A couple things i'd check into is see if there as anyone close to you that could demo their machine to you. Size is irrelevent, they all function the same way.
Also check to see if there is a shopbot camp coming up close to you and try to attend. you will get more knowledge there and network and make friends.

Ask all the questions you need to here...:D

[Joe Porter]

I notice that you are in Cleveland. Vectric is having a User Group Meeting in Cinn. next month. Look at their website for info if you are interested. These are the people that write the software that a lot of us use and you will get answers to all of your design/toolpath questions. Also, you might go ahead and visit their forum if you haven't already. I think you can download a free trial version of V-Carve or Aspire. The programs have the complete Help Manuals listed on the menu bar. There are also many tutorials on their website. As far as the ShopBot goes, you cannot go wrong for what you intend to do or anything else you might think of. I just wonder if maybe you might want a Buddy instead of the Desktop.......joe

[zeykr]

I'm not sure the 1/8th" text will be easy. The machine is capable of carving that fine, but many materials won't hold enough detail at that size and parts of the letters (the center of the A) may be lost. It can probably be done with a small engraving bit, but if you can make the text bigger it'll be easier.

A laser head is supposed to be in the works for the desktop, and it would be better suited to text this small.

[Brady Watson]

I'm not sure the 1/8th" text will be easy. The machine is capable of carving that fine, but many materials won't hold enough detail at that size and parts of the letters (the center of the A) may be lost. It can probably be done with a small engraving bit, but if you can make the text bigger it'll be easier.

A laser head is supposed to be in the works for the desktop, and it would be better suited to text this small.

Exellent point to take into consideration. When you start carving in 'micro', woodgrain starts looking & acting like OSB plywood. Sometimes plasticizing the material with a good soak of shellac or similar will aid in crisp machining.

-B

[bleeth]

Guys:
He's talking about ping pong paddles. That's not cheap ply. I would bet that an engraving bit in a desktop with it's fine resolution would pull that off. Easy to check for him. If he sends a sample of the wood to SB they can run some numbers on it and do it. I would use a single line font and just cut along vector with a shallow depth.

[jerry_stanek]

I live in Medina and you are welcome to come buy and see my prs run. M Email is jstanek2 at gmail dot com

[feinddj]

Brady's point about the material not holding up is very apt. Thin super glue is also an answer to that issue.

Upgrading to Aspire will help you with the handles. It has a 2d toolpath to surface which will allow you to check grips and or do logos on them.

David

[bcondon]

Just a thought... upgrade to Aspire but also use Brady to digitize the firs few paddles. This will get you up to speed pretty quick with accuracy in your product.

I am working with a partner now and we would include Brady's digitizing services as a way to get good results quickly...

Thanks
Bob Condon

[Ross Leidy]

Guys,
Thanks for the detailed and helpful responses. It's great that these machines generates so much enthusiasm from their owners. That is a huge plus.

In response to some of the comments - the paddles ("blades" in table tennis parlance) are composed of hand-assembled plies that I glue-up myself. The types of wood, thickness, hardness, elasticity are chosen to achieve certain blade characteristics (fast/slow, stiff/flex, soft/hard, etc). Many times I will choose an unconventional wood species to distinguish my blades, and there are many different species that I might use for the outer ply. Some, I imagine, would behave better than others for engraving small text. I'd hesitate to use any superglue on the surface since it would change both the properties of the surface and the look of the finish.

Where I really try to distinguish my blades is with the handles. I try to let the wood do the talking, like in the amboyna burl & masur birch handle below. This is an extreme example, but shows why I'm not so interested in any kind of surface texturing (checks) and more interested in overall 3D shaping of the grips. Like the blade outline templates, there are a lot of different handle templates that I currently have to manage. Having a digital equivalent would be fantastic.

Considering the handle shape below, could anyone offer an estimate of the time to cut the shape from a blank that is already milled to the desired grip thickness? Would the finish be close to that of a routed surface? I'm trying to gauge if final sanding would be more/less/the-same with a cnc-milled handle vs my current process.

I've considered a laser engraver for the small text, knowing that it would give me the detail I want, but I didn't want to have to deal with charred edges if I also used it to cut out the blade outline. That's why I'm leaning towards a cnc router. A laser head on the Desktop would give me the best of both worlds, although I can't imagine that will be a low-cost add-on.

Thanks again for your advice and direction. I appreciate it. Jerry - I'll be in touch to see if we can arrange a meeting.

http://rossleidy.com/posts/blades/yakult/20120513-DSC_3186.jpg

[rcnewcomb]

Ross, that is beautiful work. The CNC helps with consistency, but it is still dependent on the creativity of the artist/craftsman. You clearly have the creativity and an eye for detail. I'm looking forward to seeing more photos of your new creations.

[beacon14]

Wow, nice handle. I'll let the 3D guys answer the question about how long to machine. Just want to mention one thing:

"You can eliminate tear out will the proper feeds and speeds and bit combinations. No problem."

I would say you can minimize tear-out but eliminate it? I would hesitate to guarantee that. Some woods will be easy, others not so easy. In any case I would still expect to sand any surface that comes off the CNC before applying a finish. Depending on your approach there could be a little sanding or a lot. In your case using longer machine times to minimize sanding will be desirable. Unless you are trying to crank out the maximum number of parts in a day I doubt the machine time will be a big problem compared to what the CNC can do for you. I assume there are other tasks you can handle while the machine is carving those handles.

[myxpykalix]

David,
I guess i should have used a few more "qualifiers" in my sentence structure...:p lol Maybe i should have added the word "virtually" to keep me out of trouble!
You are right though, but there are so many variables with feeds/speeds/bit combinations that i didn't want to give the NEWBIE too much info to digest.

I think i'm still learning some things about that....

[Ross Leidy]

Hey, thanks for the comments on the handle.

Regarding sanding - oh yes, I fully expect to need to do that after a grip is machined. I was just trying to get a sense of how much by getting a comparison between a routed surface (roundover bit) and a cnc-milled part with a similar shape. It sounds like it could be similar with longer machine time.

I did see in a shopbot video that the software allows you to specify a climb cut, which should take care of most of my issues when cutting out the blade outline. I do use a climb cut when routing my handle grips, and I have a jig that keeps my hands well clear. But the blade template is simply a 3/4" mdf form with no holding jig, so I won't try to climb-cut with that on the router table.

Here's another question for you guys. Because I use hardwoods for the handle grips, I have to hollow the underside to bring their weight down to a reasonable level. This is another pain-point for me when setting-up for a new handle shape. I need to build a jig per shape that will hold the rough-milled grip securely flat side down, and which has a oblong hole underneath where I use a hand-held router with a guide bushing and core-box bit to create the hollow.

It would be great to incorporate this into the cnc operation. As I see it, the hollow would be incorporated into the 3D handle shape, and that the hollow would be cut first, the material flipped over, and then the handle shape would be cut. Would the 3D software handle breaking-up the operation into two steps based on cutting the top and bottom surfaces? Also, some of the handles are asymmetric, so the hollow section is, as well. Does the software deal with the change in orientation when the blank is flipped over? (I guess this is general question about indexing the work to the model.) I think if I could get an understanding of how this works and if it's ho-hum routine or overly complicated, I'll be a lot closer to a decision on whether or not cnc is for me.

Thanks again for the help and advice.

[Brady Watson]

Ross,
You must first 'digitize' your handles to get them into the computer - much like a digital mold or template. Once they are represented as a 3D entity, they can be offset to create the hollow interior. Most likely additional material would be added to the handle at both ends to facilitate hold down.

The handle is first hollowed out on the 1st side, then flipped over, using the extra material as a clamping pad or place for screws, before machining the 2nd side. When machining is complete, just remove the extra material at both ends. A thin bridge or web is usually all that is needed - although this depends on the wood species - between your finished part and the hold down blocks.

-B

[myxpykalix]

The simple answer for your two sided operation is that you would have 2 different models for the same part. A top side and a underside side. The top side is where you cut your profile on the outside of the handle. The underside is where you cutout your inside hollowing.

Or you could have one model, create your outside perimeter cuts, save all toolpaths then flip the part and create your underside hollowing and save those toolpaths. Depending on what program you use. Bottom line is it will do all your operations necessary.