Author Topic: Chip of the day. (Read 9128 times - 2 votes)
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Rob M · « **Reply #20 on:** February 15, 2020, 09:56:51 PM »

well it looks worse than i thought.. Oh well , i got a few more days of work to go.. the gantry needs to be filled with sand , the table needs to get finished and cut , goota diagnose the spindle flow issue , the collection table needs to be tested, i started spot drilling the left side in the pic , maybe im more like 80%

20200215_194922_HDR by murphyrobert9, on Flickr

Rob M · « **Reply #21 on:** February 15, 2020, 10:00:10 PM »

someone is gonna say " you reduced the work area/ travel "
I know. I dont do large engravings, or anything similar.. so i figured, 10"x by 10"y by 5 z will cover all my needs.. im gonna try my micro flycutter again also. I know it ran poorly before the coversion

Gippeto · « **Reply #22 on:** February 15, 2020, 11:26:58 PM »

Good stuff.

Far better starting point than my 3018...and further along as well.

As to cut volume...it only has to work for you...and you know what you need better than anyone else.

Not a huge fan of drill press vises for milling work, but I'm also familiar with "run with what ya got" (BTDT)...also...see above.

Most of what I do will be secured with painters tape and either super glue or foam safe spray adhesive.

Have a good bit of work to do on my gantry yet, but it should come together quick enough once the bearings get here. As the "bed" will be the next big job, I'm interested to know how well yours works out...please post updates on the project as available.

Al

Rob M · « **Reply #23 on:** February 15, 2020, 11:50:32 PM »

yea, i thought about a regular mill vice ( have one on my milling machine ) but this offered some interesting flexibilty with the tilting feature.. I could actually machine the the vice on the Mill to pretty decent parallelism as the fixed jaw is truly " fixed ".. We shall see. Im not set on using it yet.. I think my parallels will be too short .
As for the bed, go overkill.. Ive been through several variations before this,.. the 1/2 inch box steel with the aluminum plate on top has almost No flex .. this machine is odd in the sense you need to span 30 inches with No center support.. Ideally , a 30 by 19 1 inch thick piece of steel would be there , but thats 250 bux I dont feel like spending ( yes i looked into it
Really , when it comes to the table , it simply has to be stronger than the gantry or steppers will ever be,. Ive had the machine for over a year and had this in my mind for a while/. I also think with these spindle speeds, and a decent removal rate, you need flood coolant.. The difference is night and day.. The reason i say that is simple, these chinese spindles have no torque under 10k rpm , above that ur humming along but dont have the rapids to to get the cutter out of dodge in time , So the compromise when cutting aluminum is flood coolant . We will see, im no expert , i just know what i didnt like about the machine , and im changing those things.. It will never be as rigid as my milling machine , but getting it to the point where i can use the 2hp is the goal. Ill update when i actually cut something useful with it. (-'

The 3018 might be a better platform to start with , less distances to span.. Looking back on mine , Id have made it a fixed gantry , and change the Y to a moving table on 2 20mm linear rails ( use same ballscrew /ballnut etc.

MJP · « **Reply #24 on:** February 16, 2020, 06:03:22 AM »

Oh my, how have I missed this?
Al the cast parts look awesome! Just what I was planning to do as well. Got my 450gram crucible already delivered from the friendly China people.
Valves look good also.

Boys putting together cnc gantry machines, will be interesting times for sure.
Nice build you have going Rob!

Marko

MJP · « **Reply #25 on:** February 16, 2020, 06:16:09 AM »

Rob, can I make a suggestion on the side plates?
You can make the structure more rigid by bolting a scuare block in the middle of the side plate and running allthread from the ends of the plate through the block and slightly preloading the rods.
Something like this quick sketch.

Because that is now the most flexible part of your machine.

Marko

Rob M · « **Reply #26 on:** February 16, 2020, 08:21:35 AM »

i see the line.. Are you referring to the bed, or the uprights for the gantry ??

I think I see what you mean now , put some preload on the gantry uprights.. I have some 1/2 inch all thread..hmm.

MJP · « **Reply #27 on:** February 16, 2020, 09:59:49 AM »

The gantry uprights, not the most elaborate drawing from me.

You will eliminate alot of side to side moving from the gantry plates. The plates look about 12mm?
I did a thicker side plate modification to one old plasma cutter from 12 to 20mm at the university and it reduced vibration from the frame. And that was just plasma, not to mention you are milling with yours.

Marko

Rob M · « **Reply #28 on:** February 16, 2020, 10:31:11 AM »

makes perfect sense, and agreed.. theyre 15.5 mm, which isnt horrible but theyre some kinda cast chinese aluminum ( chinesium i think

Gippeto · « **Reply #29 on:** February 16, 2020, 11:14:13 AM »

Thank you Marko. Lots of projects going on, and a few have been ongoing for some time now. 450gram seems small, but I'm melting 4-ish kg of aluminum at a crack...need quite a bit of extra metal for pouring basin, sprue, runners and risers.

Rob...big steel is spendy huh?

Did you check into getting it surfaced too? I did...that's why I bought an old Rockwell table saw at the pawn shop...cast iron AND surfaced. (ok..not ground, but good enough for me) Fixed gantry made it a viable option. Still need to make something for the work table, but have a couple ideas for that.

20mm rails would be overkill to the nth degree. I'm good with overkill, but a fellow could use the money elsewhere.

Rob M · « **Reply #30 on:** February 16, 2020, 01:27:53 PM »

agreed.. yea, the giant slab of steel could be surfaced by the ,machine itself while installed. Woodworkers surface their spoil boards with large router bits that look like face mills ( not saying woodwork requires the accuracy of machining ).. but thats If the machine could mill steel well and it cant . The large box steel gantry i was able to fit on my mill table ,but the table for the cnc wouldnt fit so id need to outsource $$
i just milled a shallow 8 by 8 box section for the vice to sit in , not happy with surface finish at all , so i know my Z axis needs some tweaks. For some reason i was all home runs building my X , but when i finally got to Z i was Mr shortcut

MJP · « **Reply #31 on:** February 16, 2020, 02:16:53 PM »

I was thinking about it when I was typing but it didn't ring any bells. Yeah 4.5kg crucible. Had to check what I had ordered.
They had 1-9kg available and I took the middle of the size.

Rob, just use a fly cutter and very slow feeds, 20-40% stepover of the radius. It'll be fine for most of the setups.
Remember to use some kind of steady cooling like mist or flood.
Heavy fly cutter wont chatter as easy but your spindle needs to be mounted firmly.
Marko

Gippeto · « **Reply #32 on:** February 16, 2020, 03:26:25 PM »

Quote from: MJP on February 16, 2020, 02:16:53 PM

Yeah 4.5kg crucible. Had to check what I had ordered.

See how complicated that blasted metric system is!!! No one ever confuses lbs and ounces...

MJP · « **Reply #33 on:** February 16, 2020, 03:32:12 PM »

Naah, nothing wrong with the system, it's just my memory.

Take four different imperial measurements with fractions and try to add them up. Even you folks accustomed to that will be having hard time with it.

Marko

Rob M · « **Reply #34 on:** February 17, 2020, 01:06:29 PM »

ran a dimensional accuracy test today.. half inch hole and 1 inch square ( my y offset was wrong , doesnt matter for this )

the x was 1.011 and and the hole was .504 .. so about the same innacuracy in both axis.. gonna dial things in mach 3 see if i can get better

20200217_103639_HDR by murphyrobert9, on Flickr

Rob M · « **Reply #35 on:** February 17, 2020, 01:09:47 PM »

the bottom of the inner hole was rough , but finishing pass in f360 might help that.. this was run with easel , which has few options for cutting direction and finishing passes.
Overall , im pretty happy.. filled the gantry steel beam with sand today , much quieter , less vibration.. got a lot of things to " button up " but i think the machine is finally where it should have been from the factory (-'

another angle on the pocket

20200217_102516_HDR by murphyrobert9, on Flickr

MJP · « **Reply #36 on:** February 17, 2020, 01:14:55 PM »

You need to check the pulses per unit of movement.
Run the axis something like 100mm and check the accuracy of the movement.
Then calculate the demanded pulses and see did you over or undershoot the distance.
After that you have pulses for that given movement and you can calculate the compensation for the axis movement.

Marko

Rob M · « **Reply #37 on:** February 17, 2020, 01:16:22 PM »

thanks.. Mach 3 actually has this integrated.. it counts the steps per distance.. and does the math for you. So you tell it to jog 20mm, then enter the actual distance it jogged.. It then asks to confirm , then does the adjustment.

MJP · « **Reply #38 on:** February 17, 2020, 01:18:13 PM »

Too easy

The roughness from cutting the chips inside the pocket and not evacuating them with coolant or air. At least that's what it looks like to me.

Marko

Rob M · « **Reply #39 on:** February 17, 2020, 01:25:13 PM »

makes perfect sense.. This result still blows the stock setup out of the water. complete night and day. My ramp in and plunge rate can all be played with and try to do better... Now to actually make something useful (-'

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Chip of the day.

Author Topic: Chip of the day. (Read 9128 times - 2 votes) )

Author Topic: Chip of the day. (Read 9128 times - 2 votes)
)