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View Full Version : Maybe good time to go with a DRO



BillH
03-27-2005, 10:37 PM
I see that HF has their 6" digital calipers on sale for 15.99. Today I was machining off some thickness on some parts for my steam locomotive and realised I cant go on with no accurate height adjustment on my micro mill.
For now one of these will do.
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=47257
Hmm, the DRO does sound very interesting. Cant afford a new mill, so will make what I have work for now.

vinito
03-27-2005, 10:43 PM
I picked up one of those for just that purpose the other day (I'm using it as a scale for a Shumatech DRO (http://www.shumatech.com/products/dro-350/index.htm) that's almost installed).

They had the 4" and 12" on sale too a couple weeks ago for good prices, and the sale is likely to return.

[This message has been edited by vinito (edited 03-27-2005).]

torker
03-27-2005, 11:14 PM
Bill, I added a pair of Fowler digital calipers to the quill on my machine (poor pic)
http://img.photobucket.com/albums/v210/torker/6ec76c6a.jpg
I'd never want to be without them (or a real DRO) again. So much nicer than counting turns. I like these because you can turn them off and can rezero them anywhere you want. This is really handy for drilling holes that have different depths/sizes. Eg, holes for allen head bolts. You can drill them complete in one setup and they all turn out the same. These come in 12 and 24 inch also. I was going to mount them to the table axis also but the round tuit deal still plagues me! http://bbs.homeshopmachinist.net//biggrin.gif
Russ

torker
03-27-2005, 11:24 PM
vinito, is that kit fairly simple to build? That would be nice to have a real DRO with a readout where you can see it. That's another reason I didn't want to mount calipers for my tables. Too darn hard to see!
Russ

vinito
03-27-2005, 11:53 PM
Yes it's pretty simple.
I am an elecronics rookie but it's all gone really smoothly. I've done a little PCB soldering, but only as a hobby. If you have to learn how to solder on this project it might be a little harder, but you'd get a lot of practice. There are a LOT of solder points on the board (to my eyes) but it still only took about two or three hours to assemble the PCB including soldering, clipping off wires, and checking it over & resoldering a few points. I took my time too. I used a multimeter a couple times, but even that might not be necessary. I just used it to verify a couple things.

The case is generic so it has to be milled for all the buttons, windows and connectors. It's not too tough, but it sure would have been tons quicker with the DRO already installed - catch 22. I think it took an hour or two of relaxed machining.

The web site has good instructions for putting it together and easy links to two sources for all the parts except scales. Regarding scales, that's one thing I liked about the Shumatech design. You can use cheap chinese scales or mix and match them with any other type of scale having quadrature output (with a bit more work and expense, but still easy), or even rotary encoders. The calipers I got from HF work perfectly with it.

The trickiest part is working out and machining brackets to attach the scales to the machine, but that's not that bad either. That's what you were thinking of with the calipers already anyway.

For my requirements and budget, the Shumatech was a good fit. (Standard disclaimer here)

If you think you're interested, spend some time checking out the web site. Once the steps begin to take shape in your head, it's a relatively simple project. There is a lot of useful information on the Yahoo group site, so check that out too (there's a link to it on the Shumatech web site (http://www.shumatech.com/products/dro-350/index.htm)).

All I have left is making brackets and attaching it to the machine. Too many emergencies have popped up or it would already be done.

BTW, It depends mostly on how much you pay for scales (about $90 total in my case), but I'll have about $200 total in the working unit and it's going on a full-size Gorton mill.

[This message has been edited by vinito (edited 03-28-2005).]

spkrman15
03-28-2005, 07:35 AM
vinito,

so you can use any set of scales that have the 4 pins? This looks way too cool. How do you program it? Have a link from the computer to the DRO unit?

Rob http://bbs.homeshopmachinist.net//smile.gif

BillH
03-28-2005, 09:36 AM
You can upgrade it via serial cable from the computer. You know, I think my southbend 9c is going to get a DRO as well, lol.

vinito
03-28-2005, 11:51 AM
lol. Yea that's what I was thinking too, Bill. For $200 a pop there might eventually be a few of them scattered around my shop. Then I realized my lathe needs a 4-foot scale and might be a little higher. Maybe I'll be lucky and run across one for cheap someday.

Rob,
Bill's got it. There's free software and instructions for programming the chip on the web site. A circuit for programming the chip is built into the board & all you need is a serial cable. If there are future upgrades, you can reprogram the DRO in about 2 minutes from your PC.
Apparently all the cheap chinese scales and calipers have the same output protocol. The DRO was designed to read that protocol, but there is a cheap & simple add-on that translates quadrature scales into the chinese scale protocol so the DRO can use them. That opens up a bunch of other possibilities, but there are still other output types that are not compatible with it so you need to know what kind of scale you have to know whether it will work or not.
That's about the extent of my knowledge.

dvk
03-28-2005, 11:52 AM
Bill I'm asuming your using the micro downfeed for height adjustment, when I used that when I was milling the micro feed would pull itself down making a ramping cut deeper into the work.
I locked it with the set screw on thwe dial on the right side but I just was not able to get that accuracy of depth of cut to the .001". I was needing.
So I got rid of the drilling feature and locked everything up at the headstock, so now the whole quill becomes the height adjustment, and by using a magnet base dial indicator on the right side I'm able to get the height adj. I need to the .0005" if needed. It has worked real well.
I could post a pic if ya like, but thought I would share what worked for my micro-mill.

BillH
03-28-2005, 12:55 PM
DVK, that is exactly what I have done, I have locked the downfeed, and only move the entire head for height. Strange I haven't thought about using my dial indicator on a magnet that I use quite often for the lathe, geez,its a quick fix for sure for now, thanks. I think I will still get that digital caliper though or 2 and start getting ready for the eventual DRO.

Vinito, I think a quadrature encoder for the bed on the lathe would be easier, could use a rotary indicator with a stainless steel wire on a pulley setup, but I wonder how accurate that will be with temperature change.

vinito
03-28-2005, 01:25 PM
Nah. I think the only thing I'd be happy with is probably a glass (linear) scale. It will be more pricey or I need a little luck, but for a long axis like that it might be worth getting a stable, accurate scale. The Jenix scales appear to be pretty nice for the money - already covered and comes with armored cable. I'm so broke right now I can't even pay attention, so I'm in no hurry anyway. Maybe something will come up.

hoffman
03-28-2005, 06:13 PM
I can relate to the lack of $$. I'll have an extra grand or so by the end of the month so I'm thinking about springing for a DRO for the mill. That's a butt-load of cash to me but I think it'll be worth it.
Machining be expensive...

------------------
Hoffman in Warner Robins Ga

John Stevenson
03-28-2005, 07:11 PM
Some information on the Shumatech DRO.

As it stands it is designed to read the Chinese scales and gives a resolution of 0.0005"
It is programmed from a PC via a serial cable and software that is on the home site.
There are three versions of the software.
The early version that was for lathe or mill.
This has been superceeded but the program has been left for the people who run 3 in 1 machines.
The other two programs are dedicated mill and lathe programs.
The core part of the program is identical but they differ in the options.
Mill has bolt circle and centre / edge finding lathe has diameter mode and 9 tool offsets.

With the addition of a small extra board called a QC100 the same unit can read glass scales. You need one board per axis but you can mix and match. i.e. chinese scale on one encoder or linear on another.

I have one of these on a 14 x 40 lathe.
It's carrying a chinese scale on the cross slide and is setup for an encoder on the bed axis but that hasn't been done as yet.
What I proposed to do was to mount a fine knurling wheel hard onto a machined part of the rear bed that isn't used and keep runnig the carriage up and down until it produced a 'rack'. Then mount an encoder on the knurl shaft.
Even if I can only get 5 thou accuracy it's enough for what I do. At the moment I'm using the handwheel dial and a rule so 5 thou is good enough but I can't see why i can't get better. The encoder input is tunable by programming at the box so it can be set as accurate as needed.

For thoose who need the accracy of linear scales go to the Shumatech site and join the group.
http://groups.yahoo.com/group/ShumaTech/

Then go to the files section and read the blurb on the Jennix scales.
Tim at Linear Measuring Systems has arranged a deal with group mermbers on Jennix scale pricing and believe me you will be pleasantly suprised.
The price list is in the files section.

For anyone who doesn't feel confident f you ask there are people on the list who will build one for you and test it. Cases are also available form various people.

Anyone living in the UK or Europe can contact Lester Caine who is acting as the UK agent for Scott and has boards, kits and cases.
His contact details are on the order form on the web site.
http://www.shumatech.com/

Just thought this might claer a few things up.

John S.