Will a PRSalpha BT48 be the best solution for my Makerspace and contract work?

[johnschneider89]

I'm in the process of starting up a makerspace in Fargo, ND and while I think that the PRSalpha BT48 will be the best solution for me, I'd appreciate any input current owners might have.

This will be a tool that will be used primarily by hobbyists (who have been trained in operating it), for project-based classes, and for contract work.

I know that for the contract work, at least one of the projects will consist of cutting out pieces for children's furniture out of full sheets of 1/2" Medex, so I'll be needing to purchase the 8' powerstick.

The reason I'm reluctant to go with a full-sized ShopBot is due to two reasons. Limited space: I'm only going to have 2000 square feet to work with, and the ability to move the Buddy against the wall and take up less space is rather attractive to me. Reason 2? I'm likely going to need to partially disassemble the Buddy to fit it through the door, I'm certain I'd have to disassemble a full-sized Bot to get it inside.

Any thoughts?

[zeykr]

The full size bot comes disassembled and you put it together.

The buddy with a power stick takes up twice the room cutting full sheets as does a 4x8.

If it were me, I'd probably go with a 5x8 machine.

[johnschneider89]

Thanks Ken, wouldn't have known that otherwise. What advantage does a 5x8 machine have over the 4x8? Wouldn't both be able to accommodate a full 4x8 sheet of material?

[zeykr]

The 5x8 can handle baltic birch that comes in 5x5's for very little extra room or cost.

[Bob Eustace]

John you really need to look into your crystal ball! Will you possibly be turning later on? The Buddy has very little room for this. Will you need to hold anything vertically such as tenons, perhaps dovetails etc? The Buddy cant do this at all as it is solid steel under the head. With the Buddy unless you follow Andrews excellent advice on this page with regard to table flatness this can haunt you a wee bit as the seasons change UNLESS you lash out on an aluminium frame or phenolic top. Vacuum is very limited on the Buddy - we use the puck system but its no where near as good as conventional on large sheets. I reckon when Shopbot designed the Buddy they had the feeling that they could create a new market for CNC on the construction site. This doesnt seem to have happened even though it is a beautifully made machine. I really do worry though about the load on the X axis when machining very heavy fence rails. You cant seem to get an exact definition out of Shopbot as to the maximum loading. If you have little room the Buddy is very adaptable to a small space when needed BUT changing out power sticks is not as easy as one would think and they are not all exactly the same width so you get slop that is not easily adjusted out if you are old and cant lay on the floor! The dust collection on both systems is poor compared with the Kent method. As Ken says though, the thing just wheels out of the crate ready to go as soon as you hook up juice and the spindle.

However John you are halfway there as you have picked the best value machine money can buy with the best support and you just cant put into words the value of this forum. No matter how dumb the question you just never get flamed! As a suggestion I reckon if you repost your query in the general section you might get more comment from non Buddy users.

[dana_swift]

I have to disagree with Bob about the Buddy and the use of vacuum. You can set up almost anything you want on a Buddy.

Here is my vacuum setup photos for my BT-32:

http://www.talkshopbot.com/forum/showpost.php?p=22179&postcount=16

Pucks work and are handy, but you can have a full vacuum table, and still remove it to use conventional hold down with a buddy. That is not practical on a gantry type SB.

Vacuum is not limited in any way on a Buddy, it requires a little "figuring" on how to make it work your way, thats all.

:)

Otherwise I am in full agreement with Bob's advice!

D

[steve_g]

Dana...
So if my quick look at your link is correct, you lost 1.5" inches of Z with your system?

SG

[beacon14]

You can not beat the convenience of cutting full sheets on a gantry machine compared to a Buddy. I would buy the machine you can grow into. Another benefit of the larger table is that if you have one person who has to keep a jig secured to the table for a few days someone else could cut another project on another part of the table.

[Bob Eustace]

Dana I follow your posts like a hawk but sadly missed the one on your superb vac table! Beautiful work as usual like your guitars! From memory you have an original Buddy with the aluminium table??? Reckon in a perfect world the ideal shop would have a Desktop for labelling etc, a gantry for sheet and a Buddy for the smaller bits. My "treasurer." wont allow this unless I shed some of my beloved keyboards! Our next tool has to be a Festool Kapex as I am getting health problems with Makita despite the best efforts on the Bot to shield the thing. I think a lot of the guys on You Tube are fooling themselve on mitre saws.
As you probably guessed we are busily woking away copying Andrews brillianlly thought out edge leveller. Chrissy upgraded her APQS quilting machine to CNC last year and a fantastic set of 10 guide wheels came with it. As the existing ones were fine she gave them to me yesterday on the understanding that I complete several outstanding jobs for her! Thems the breakes.

We use your idea David even on the Buddy. We have a long run job set up on one side at present with "problems" but we merrily work away on the back of the table so one doesnt starve to death!

[Simops]

- we use the puck system but its no where near as good as conventional on large

Bob....pardon my ignorance but what the heck is a "Puck system"?

Cheers

[Bob Eustace]

Hi Mike - I think I showed you these when you came up but we did cover heaps of stuff. Just do a search on ebay for vacuum hold downs. About $70 a set of four from a great guy Lance Woodbine in the States. I use them to hold down plastic trophies. Runs off your air compressor. You can get them also in rectangular form from Carbatec and Machinary Wharehouse - $70 to $99 for around 10 inch by 12 inch. You can however EASILY make this stuff on your Buddy by using one of your wifes cutting boards! Ben at Mach Wharehouse also sells the rubber sealing tape.

[Simops]

Bob don't remember seeing them at your workshop but probably too busy looking at other things.....

Anyhow I know what you mean now as I've seen them at Carba-tec.

Anyhow Bob I think I have to seriously look at what Dana did for a vacuum solution to his Buddy. I cut quite a bit of 2mm aluminium and my present hold down of using screws and double sided tape is not the way to go. A vacuum table solution, I think, is the way to go. Dana uses HDPE and recently I had to buy some for a project. Well talking about price.....it's expensive stuff here. To do a 48 x 48 table the way Dana did would cost me a few hundred dollars in HDPE alone!!!

Cheers

[dana_swift]

@Steve Yes- the vacuum table takes right at 1.5". But the vacuum is for sheet oriented things, so thickness is not an issue. I think of it as when I shut the pump off, and unbolt the vacuum table I get an extra 1.5"! For those of you who didn't notice the detail- my vacuum table bolts onto the table base so its solid as a rock. I have been using the same vacuum table unmodified since I first built it. So its got a good 4+ years on it now. If I had to do it over, I might make it thinner, I think I could make it work just as well where the HDPE layers are only a half or 3/4 total thickness. The thickness of the HDPE was partly chosen to allow the manifold on the side where the three vacuum hoses attach. For any dedicated cutting I have made purpose-built high-vacuum fixtures to hold parts while I cut/shape them. The dedicated fixtures are bolted to the main table. Hope that makes sense- D

[dana_swift]

@DaveB I have to agree about the full gantry and full sheet cutting! I think the buddy is great if you only want to do a full sheet once in a blue moon. FabLabTulsa has a 48x96 alpha with a spindle, and I DO use it when I cut full sheets. That isn't often, but its vastly superior for the big jobs. Its like having the best of both worlds. @Michael I used HDPE, but plywood would have worked fine! Perhaps better ;) If you have good plywood available, I would give it a go. Save the cash for when you decide to fly me down to help you dispose of a couple Fosters! (I'd be happy to bring you some of our brew for compensation.) D

[pkirby]

Here is my vacuum setup photos for my BT-32:

http://www.talkshopbot.com/forum/showpost.php?p=22179&postcount=16

D

Dana,
Nice setup! Do you have any other posts regarding the details of the system? I'm most interested in how you are pulling 20"Hg with unsealed Trupan?

Thanks,
Paul

[gerryv]

Thanks Dana. I'm about to build 2', 4' and 8' powerstick vac hold-downs and was giving pucks/pods a serious look. I like your results by comparison as well as the added benefit of cutting into a spoil board rather than into the relatively shallow gasketing used on the pucks/pods. What is your vac. source?

[Bob Eustace]

Mike
We are getting a sample for trial cuts today (if it stops raining as the load is all MDF!) of a new product called Nema. An 8 by 4 in 3/4 is only $121 and you can get it in inch for $252. It looks great finish wise but no where near as dense as HDPE. Dont forget you can get recycled plastic sheet in Adelaide.

http://www.cowdroy.com.au/nemaboard.htm

If you want to give yoursrelf a heart attack ring up for a quote on 48 x 48 x 1 flat aluminium plate as a table replacement. First guy wanted $2100!!!!!! The recyclers brought this down to $1200. Danas plywood suggestioin souinds like a good move. All Boards in Jersey Road Bayswater are bringing in Russian Birch that looks to be OK BUT being a scrooge I would go for the 3/4 formply with the black plastic coating. We are machining this and engraving with superb results as the stuff just has no voids - seal the edges and it would have to hold vacuum. Bunnings - $78 for 8 by 4. They have handyman sized bits for $15 if you want to give it a try.

[dana_swift]

(@Paul The trupan WAS sealed on the sides, it HAS to be or the leakage kills the vacuum.) I am currently experimenting with other bleeder materials, and semi-custom dedicated bleeder material on top of the HDPE shown in my earlier photos.

As to other posts with details, how about this one?

http://www.talkshopbot.com/forum/showpost.php?p=133034&postcount=2

(When I read that older post, I said in error that the max vacuum for the KVT was 28" Hg, its NOT, its actually 27".) I limit that pump to 24" with a vacuum-pressure shutoff to keep vane wear down a bit. I am still on my original set of vanes (hopefully will be for a while).

In the years since I built my vacuum system, I bought a much smaller Gast vane pump, so now I have two high vacuum pumps I can switch on in various combinations. The good news is for most of my dedicated fixtures the Gast is adequate, but if I get any leakage I turn on the Becker KVT-140 and it gets noisy but it keeps the vaccum up with high(er) flow.

As to other details, I have two vacuum accumulators, one "was" a 100LB propane tank (I still get the Mercaptan odor when I pump it down! It must be slow to evaporate off the steel walls..). That accumulator is only for the Becker pump, there is another small accumulator which "was" a (15 LB?) freon bottle, which is used for the Gast pump. The two vacuum sources feed a manifold through check valves made from dog balls and PVC (read up elsewhere on this site) so the pumps can be run individually or in parallel.

I built an electronic vacuum pressure controller to switch the Becker on and off so it does not run continuously unless there is a serious leak. It kicks on any time the pressure is below 18" Hg. It has a digital pressure readout that reads to 0.1" Hg. I can keep an eye on changes in pressure very nicely with it. I can see if the leakage is increasing or holding steady with enough time to add masking tape to the cut-through areas long before the vacuum drops to "nervous" levels.

The Gast will pull a reliable 29" but has very little flow, my recollection is its a 3/4 horse model, I would have to go look to be sure. I rarely see it at 29" tho, when I open the vacuum valve to hold the part it finds a steady state in the 20's of inches of mercury. That is only for non-cut-through parts. If I am cutting through, its Becker time (watch that electric meter spin!). Even then I like my vacuum over 15" Hg, it just makes me feel good to know nothing is going to shift.

The vanes in the vane pumps I use last longer if the vacuum is lower. The graphite vanes would have less force on them and wear slower and that is something I would like for a future improvement.

Which brings up another point, making vacuum fixtures out of HDPE is not as good of an idea as I thought it would be. There is no leakage at all, but HDPE is VERY slippery! Its also not very rigid and can flex causing setup troubles. Future fixtures will not be made from HDPE, but most of my current ones are. Having a material with more friction where its in contact with the stock being machined would probably get me more comfortable with lower vacuum pressures, and I might run at the 5-7" Hg type numbers that are more typical in other posts. My fixtures do use AllStar gasket tape which makes a very good seal and helps with the friction issue.

Enough for now..

D

[dana_swift]

@Bob- thanks for the tip on Nema board, that looks like a very interesting material and may be just what I am looking for to replace HDPE. I will have to see if any suppliers around here have any.

What does a 4x8 of half inch (12mm) run you in Aus$?

Unfortunately NEMA to me means "National Electrical Manufacturers Association", so it seems odd to say "Nema" and board in the same sentence.. sigh.

D

[Simops]

Mike
We are getting a sample for trial cuts today (if it stops raining as the load is all MDF!) of a new product called Nema. An 8 by 4 in 3/4 is only $121 and you can get it in inch for $252. It looks great finish wise but no where near as dense as HDPE. Dont forget you can get recycled plastic sheet in Adelaide.

[url]http://www.cowdroy.com.au/nemaboard.htm

Hi Bob....interesting.......let me know this stuff works out.

Cheers

[Bob Eustace]

Dana - its $100 for 12mm.

[Simops]

@Michael I used HDPE, but plywood would have worked fine! Perhaps better ;) If you have good plywood available, I would give it a go. Save the cash for when you decide to fly me down to help you dispose of a couple Fosters! (I'd be happy to bring you some of our brew for compensation.) D

Hey Dana......if you make it down under its my shout! Probably not the best time to come here with the strength of the Aussie dollar....it's no longer the Aussie peso it once was! A few years ago you could of almost doubled your money coming here.

Cheers

[johnschneider89]

From the sounds of it, I think I'll be going with a full-sized ShopBot! I already know I'll have one contracted customer who will primarily working with 4 x 8 x 1/2" Medex, so I know that even if I had a Buddy, I'd probably have the 8' powerstick attached a good chunk of the time, which would defeat the purpose of the Buddy's smaller footprint.

My other question is how much of a noise difference is there between operating with a spindle vs. the PC router? From what I've picked up from reading the boards so far is that a spindle is quieter, but I'm just not sure how much quieter. I'm pretty sure I'll be going with a spindle, but it's nice to get a better feel before I pull the trigger on something (even if that trigger is just in my brain at the moment :))

[MogulTx]

SPINDLE! The router is ALWAYS loud. The spindle is very quiet under about 13K and I do a fair amount of cutting at and under 13K- so it makes it far more pleasant!

[johnschneider89]

SPINDLE! The router is ALWAYS loud. The spindle is very quiet under about 13K and I do a fair amount of cutting at and under 13K- so it makes it far more pleasant!

What is something you could compare it to in terms of how loud the spindle is? While not cutting something, of course, but just running at operating speed.

[steve_g]

You can carry on a conversation...

SG

[johnschneider89]

Steve, that's wonderful to hear! Thanks.

[pkirby]

Dana,
Thanks for all the great info. Sorry to everybody else for getting off topic from the original post :o