Will I be happy with a Desktop?

[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.