Will I be happy with a Desktop?

[JohnCoker]

I have been using a big Alpha at the local TechShop for many years, but most of what I do could be done by the Desktop and I'm seriously considering buying one for my home shop (with the spindle).

Before I do, though, I want to make sure it's not a mistake. The table size is obvious. What else am I going to miss from the big brother and is it critical?

I'm not too concerned about the cutting speed (I'm a hobbyist and cutting mostly one-off parts), but I do care about accuracy and quality of cut. Will the desktop (w/ spindle) give me the same results (at reduced feed rates)?

The other thing is the Z travel; it's a shame that there is only 4" of space in there. I mostly cut flat stock (plywood, aluminum and plastics) so I think it'll be OK, but I'm curious how often this limitation bites you.

Anything else that I'm going to be disappointed by?

[garyr6]

Oh sometimes I wish I had more Z but then I want to be taller and better look'en too.
I don't think I've ever heard of anybody being disappointed with the desktop. They may have a job that could use a bigger machine but never that the desktop could not do what they wanted it to do. Its a great machine, if you doubt it, try fined a used one at any kind of discount.

[Brady Watson]

It will do everything that Alpha will do, just a little slower. Max usable Z is about 2" when you factor in Max Z movement of about 4.125", the length of the tool + safeZ height. You can monkey around with mounting the spindle a little lower (holes already there) & remove the AL extrusions on the bed to gain some more Z clearance (extrusions are completely removable with no harm done) - but this doesn't increase the stroke of the Z, which is pegged at about 4.125". It would be rare to cut many things over 2" thick anyway, so this isn't much of a problem.

I've owned all kinds of ShopBot's for the past 13 years or so & the Desktop impresses me the most out of all of them. It's made for real work & there are plenty of companies out there running them in production - so it isn't just for tinkering, it can do real work.

-B

[myxpykalix]

I have a 5'x10' with an indexer bay (it's a monster) but i bet 75% of the stuff i do is confined to a 2'x2' area in the 0,0 corner of the table. I have never had anyone ask me to do some project that i couldn't accomodate because of table size limitations. That was why i opted for the biggest model at the time.

If you have access to the larger unit then you can do larger stuff there and use the desktop for smaller stuff. Additionally several guys have figured ways of indexing their work to make larger things on their smaller units.

A thought just occurred to me...the handibot is setup so it can index and make any size piece you want with jigging. I don't know enough about it but couldn't you somehow use that?:confused:

[scottp55]

Other than the 24" width limitation no problem indexing and feeding large stock through. Haven't had the spindle bog down at all, and love the accuracy with small bits. Could use some more Z but haven't needed it. Do wish the extrusions extended another 1-2" on X,Y 0 side for jigging so could use full table size but .
We like it so much our second one is in transit to Boston right now and we get it Monday. I WOULD have Shopbot install additional prox switches(about a $100) on all 3 axis as we work very close to the limits and it's saved us from losing position MANY times especially Z. We will be doing production on the second. You'll Love it.:)

[scottp55]

Oh, ask Dianne to have Gordon fab you a spindle/interlock like the big boys have. Gordon did a slick job and they will be standard but not quite yet. Easy on/off for air cuts and finding the best vibration free move speeds. Safer too.

[Hoytbasses]

I'm a complete rookie at CNC but we've been very happy with the desktop at the high school I work at. We're cutting electric guitar bodies (1.75" thick) and are now reliably cutting them (zero the Z off the table for thicker stuff.....we killed quite a few test bodies figuring this out) ... plus signs, small cabinets and now .060 mother of pearl inlay. All of it with great accuracy.

for my personal needs, it will work just fine (IF) I can teach myself how to tile longer parts with consistent accuracy (so I can rough out bass guitar necks with it as well as some small cabinet parts. But that's the operator's issue, not the machine....:o. I'm not too far away from retiring from teaching, so a Desktop is on my 'stuff to purchase' list. If I ultimately think I need to upgrade, I know I can sell the desktop in a heartbeat!

it handles the rigors of high school kids like a champ as the machine is pretty bulletproof!

I say do it!

kfh

[shilala]

Karl made a great point. If you find in the future that you need more machine, the desktop will sell very well at a very small loss. Probably just your shipping cost and a small %age.

I stressed over the "big enough?" thing when I got my BT48. I have never had need or desire for a bigger machine, but I don't work in sheet goods like a cabinet shop.
If I were making cabinets, I'd just cut the sheets up and then go to the bot with them to finish up. That'd be a bit more time consuming, but very doable.

I bet well over half, and probably a lot more of my work is in a 2'x2' area. For furniture parts, I need the 4'x4'. I couldn't imagine trying to index and feed that stuff.

[zeykr]

And you've got the big one at tech shop to fall back on on those occasions when you need it!

[Chazz]

I would say that the Z is the biggest limitation for me. I will be experimenting with cutting a 2'x4' bit in three steps later today. It is just less convenient and you have more things to pay attention to. So that leaves the hard limits of 24" wide and realistically about 2" usable Z. Perhaps, with more games and such, you can get 3" or so if you are only surface planing and the like. I would have liked to have a Buddy; but I really don't have the room for that -- or the extra cash.

In short, I am happy with my Shopbot.

[JohnCoker]

I would say that the Z is the biggest limitation for me.
Yeah, this is what worries me most. However, my major use case is cutting pieces out of sheet goods (usually 1/2" or less in thickness), so I expect it to be OK.

It seems curious that the 4" of travel are arranged so that half of it is lost. Wouldn't just raising the car/spindle farther from the deck give you more usable Z range (with a cutting tool installed)?

[Chazz]

In order to cut into the material 2", you need at least 2" of the bit exposed and you need to pull it out of that area... I have also found some bits that it would he hard to get 2" exposed out of the collet and feel like it was properly held. Then there is the thickness of the MDF baseboard.... All-in-all, I would have felt MUCH better with 6" travel. However, I am still happy.

[JohnCoker]

By the way, I have placed an order for a desktop. So thanks for the encouragement all!

[scottp55]

Congratulation John, You won't be disappointed. The wait begins:) Study SB3.

[JohnCoker]

Study SB3.
What's "SB3"? I'm expecting to use the same tool chain and techniques with the Desktop as the Alpha; is there something to watch out for?

[scottp55]

No John, I Just flew by you had Alpha experience,sorry. Has it shipped?

[JohnCoker]

Yep, it arrived Friday and I set it up yesterday!

[gsartor_1999]

I have been very happy with the Desktop in a middle school environment. It can handle all sorts of things and performs very well with a constant influx of newbies. I was going to get a bigger machine but that would have eaten up more space and materials. This way, I keep the projects small.

[rlwagner]

I spent a couple of months researching the three major small CNC machines: SB Desktop, Legacy Explorer, and Shark Black Diamond.

I used the Explorer at a show and was impressed with its construction and it's auto-Z setting feature. But it had no T-track table and a limit of 3" of Z cutting. So I crossed it off the list.

Then I used a friend's SB Desktop and liked it a lot.

But the Black Diamond had a huge size advantage with a full 25" x 25" x 7" cutting volume. And it costs $1,000 less than the other two. Seemed like a no-brainer to me, so I ordered one.

As soon as I opened the box, I realized that the term "no-brainer" applied to me in this case. The d___ thing is made of plastic! I felt stupid for buying the only one I'd never touched before. But it had that 7" of Z!! So I set it up and tried it.

If you saw one work, you'd have a different perspective on this Z discussion. The extra height comes at the expense of more leverage on the frame to cause flexing. Add that long Z to plastic construction and you end up with inaccurate and inconsistent depths.

I was flamed on the Shark forum for daring to protest the plastic and the inaccuracy. My fave was "It's a poor craftsman who blames his tools." Their solution was simple: just slow the feed rates way down, make multiple, shallow cuts, and then make a final very slow cut of about 0.01" or 0.02" and then you'll get perfect depth accuracy.

Except that I can't stay awake that long watching it run, and run, and run. Or more like crawl, and crawl, and crawl, and crawl! Even when slowed WAY down, however, it was never consistently accurate.

So it took my VCarve files to my SB friend. I about freaked out when he started cutting because he was just blasting through the wood---from my slowed-down Shark experience that is. I asked him to slow down and he chuckled and said to watch and learn. The cuts were all consistent, with depths accurate to within 0.01". And it was so fast!!!

I boxed up the Shark the next day and I'm getting a refund.

So, I wasted six weeks because of the siren-song of 7" of Z. I don't think it was all due to the 7", though. I think that a 4" Shark would still flex because it's still plastic. And I suspect that even the rugged SB Desktop might flex if it the gantry could give us 7" of Z.

More Z would be nice, but I won't complain, because I'd rather have the rock-solid gantry of the SB, and the accurate results it produces.

There are always trade-offs. If your #1 need is deep Z, then try a Shark Black Diamond, but not if you're expecting to cut highly accurate production parts, without needing a nap while it's running, um, I mean crawling.

[JohnCoker]

More Z would be nice, but I won't complain, because I'd rather have the rock-solid gantry of the SB, and the accurate results it produces.
It looks like the Desktop now has another 1.5" of Z travel (two months after I bought mine). So far, I haven't needed the extra Z, but it would almost make the indexer useful.

[Keyco Wood]

I am glad you got a refund. I purchased a used shark after meeting a shopbotter, did not think I could afford the bot and still have not for one reason or another. Got garage wired, still no shopbot. I did make a small profit on the re-sale of used shark. I am still sponging off a bot owner, Heck, i can't even afford the software!!! Maybe next year. Now i sound like a cubs fan... go cardinals.

[banjomanwv]

I just bought one and I love it, super easy to operate and so far its been a dream

[JohnCoker]

Since this thread is still active, I'll answer my own question: yes, I am extremely happy with my Desktop! I have made many parts with it and keep finding new uses.

[scottp55]

:) :) John.
Might as well toss my 2 cents in. I'm constantly reminded and am thankful for how precise and repeatable the Desktop is. The smaller and more intricate the design is, the more I'm grateful we didn't "Save" money by going a less rigid machine and skipping the spindle. Now with the new Z-mod, still more we can do.
Especially as Dad now wants me to try Vinlay 2" buttons!!:eek: