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View Full Version : I'm new here and in the research stage. would a X Y mill table be good for CNC proj?



trilect
12-02-2004, 01:05 PM
I've been thinking about building a small CNC router for wood and plastics. I'm thinking a 9" x 11" x y travel good enough for a first attempt. I've seen many x y tables on ebay for around 80 bucks that fit my travel requirements.

Question is this, could I use a table like this without changing screws, and use cog belt pulleys to affix my steppers to the screws?

I thought this might save me some time in the building process and give me a usable machine to help build a larger machine.

Thanks
Sam Gordon
Louisville, KY

sendkeys
12-02-2004, 01:34 PM
Alot of reports of the tables on ebay. is they tables are really nice but the screws and bearings suck. So if you dont want to deal with backlash you will have to change them. If your talking about the heavy iron mill tables. If this is a router i wouldnt think you need a heavy table like that. maybe you should think about linear slides like
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=42899&item=3856267792&rd=1

or the drillrod setup. Works for most people just fine.

ViperTX
12-02-2004, 02:28 PM
trilect...take a look at Swede's page http://www.5bears.com he used the top of one of those $80 tables for his small mill.

trilect
12-02-2004, 03:53 PM
Wow thats a nice project, too pricey for me though. I'll have to start with something less expensive with less required tooling.

I've been a acad drafter for 15 years and my home shop consists of.

1 circular saw, 1 jig saw, dremel tool. Lots of electronic tools though I build audio amps and tinker.

ViperTX
12-02-2004, 05:24 PM
Let's see http://www.buildyouridea.com is another less pricey approach. But let's think about it....2 rails or linear bearings for each axis....figure $60 per rail...so $240 for the rails for the x and y axis....then you could buy a premade z axis from http://www.cnconabudget.com for about $125 (with a sepper included) so, you need 2 more steppers ($70 each) and then you'll need a 3 axis driver which will run from $125 to $300(for Geckos), then there are the ballscrews...figure a $1.20 per inch for the rolled ones, ballnuts figure $50 for each axis (x and y) and then there is the power supply stuff...$125. Plus the aluminum for the gantry, table top, table support, etc. I should total this up in a spreadsheet for the rest of the CNC crowd.

trilect
12-02-2004, 08:46 PM
Well I've looked thru my junk collection and found a few scavenged printer slide bearings. I found one slo syn 250 oz holding stepper (no idea where this came from) a few useless printer steppers. I can green sand cast some rough items.

I guess I'll go the hdpe plastic material way. linear slide bearings from ebay and acme screws with nylon nuts.

I think controller wise I'll go xylotek, if I need more current I think I can add powermosfets between the motor phases and the controller. I own acad 2004 already.

ViperTX
12-03-2004, 11:34 AM
Well I've looked thru my junk collection and found a few scavenged printer slide bearings. I found one slo syn 250 oz holding stepper (no idea where this came from) a few useless printer steppers. I can green sand cast some rough items.

I guess I'll go the hdpe plastic material way. linear slide bearings from ebay and acme screws with nylon nuts.

I think controller wise I'll go xylotek, if I need more current I think I can add powermosfets between the motor phases and the controller. I own acad 2004 already.

Cool, don't let the analysis paralyze you.

I just bought 2 linear rails with 2 trucks each on Ebay for $78....they are used...but look to be in great shape...we'll see. The rails are about 18 inches long. I've contacted the HiWin distributor in the US for pricing on brand new ones.

trilect
12-03-2004, 02:34 PM
Cool, don't let the analysis paralyze you.

I just bought 2 linear rails with 2 trucks each on Ebay for $78....they are used...but look to be in great shape...we'll see. The rails are about 18 inches long. I've contacted the HiWin distributor in the US for pricing on brand new ones.


Some prices are starting to scare me, I just have to build one though. Perhaps cheap cheap at first for the learning experience.

I've OK'd the purchase of a 3 in one lathe for the spring and a nice little building, after I'm setup with this outfit I want to get serious.

My hope is that I can eventually use a home built cnc to make forms for my sand casting hobby.

sendkeys
12-03-2004, 02:42 PM
If your thinking about prices. maybe if you want to get in you should go with a cnc foam cutter . then you can use the foam cutter with your sand casting.
also make sure you check into cnc programs cost. most foam cutting cnc software i seen doesnt cost to to much.

im sure you know about lost foam casting already but if not there alot of websites about it.


just a idea :) cnc routers arent that cheap for sure.

ViperTX
12-03-2004, 02:43 PM
trilect,
The main thing is to get started, you'll learn alot.

What sort of castings? I've done "lost wax" castings for jewelery.

trilect
12-03-2004, 03:22 PM
trilect,
The main thing is to get started, you'll learn alot.

What sort of castings? I've done "lost wax" castings for jewelery.


Greensand casting, aluminum and zinc alloy only. Its all self made equipment off the internet, I've done aluminum car plates, plaques, alternator brackets for a couple tractors and I'm working on a gingery lathe (trying to teach myself more about lathes by building one). All my sandcasting is down for this year though, its getting too cold to make the molds (outside).

I'll try to post a pic or 2 of my ugly furnace in action.

ViperTX
12-03-2004, 04:31 PM
Cool...are you using the petro sand...I think that was the trade name? Forced air furnance?

biggerrigg
12-04-2004, 12:16 AM
ah another caster diving into cnc! Me too. Maybe we can help each other out as I am building my gantry as we speak. Had to build another furnace to do cast the bigger parts for my machine. I went for the big stuff 11/2in rails and screws and closed loop servo system. I still need to choose a controller and software but thats it I will have all my parts ready to start building. If you dont mind i/m me and I will send a pic of my first part that I have in foam ready to cast. I would like a second opion on my use of foam as I need to make 2 of these parts and would like to use the cast part as a patteren for the other part but I dont know if I have enuff draft to make it work.
Aaron

trilect
12-04-2004, 06:43 PM
Cool...are you using the petro sand...I think that was the trade name? Forced air furnance?

I'm using standard water tempered bentonite sand 170 mesh though, I get it free from a local foundry. When I started out I talked to a foundry to get a few hints and tips, I left with 500 pounds of free sand, a free aluminum snap flask and a bag of parting dust. Super nice guys, I donate a little time when I can and help them out when they get backed up.

My forge is an old 30 pound propane cylinder lined with furnace cement and pearl lite. My burner is based on the monster burner design floating around. I can achieve a full quart melt in 7 min. I have a get a building up and find a good hiding place for my scrap metal to keep the wife happy.

trilect
12-04-2004, 06:48 PM
ah another caster diving into cnc! Me too. Maybe we can help each other out as I am building my gantry as we speak. Had to build another furnace to do cast the bigger parts for my machine. I went for the big stuff 11/2in rails and screws and closed loop servo system. I still need to choose a controller and software but thats it I will have all my parts ready to start building. If you dont mind i/m me and I will send a pic of my first part that I have in foam ready to cast. I would like a second opion on my use of foam as I need to make 2 of these parts and would like to use the cast part as a patteren for the other part but I dont know if I have enuff draft to make it work.
Aaron

I haven't done any lost foam casting yet, a friend told me that I might want to coat my foam form with a mixture of plumbago and molassas water, he said it would make the surface smoother.