-
17-12-2010 #51
ill do a sketch if i find time.
Why do you want such a high ratio anyway?
i may well use timing belts and pullies, im not fully commited to one thing or another at the moment
with all the ice i managed to burn out my windscreen wiper motor so iv even pulled the old one apart to look at the worm gear as a possibility... thats 55:1 ratio, i think id struggle tameing the backlash on that though
-
17-12-2010 #52
Jonathan any type of wood table is going to fail to sufficiently clamp metal to it
Whatever you are machining/clamping to the table has to be weaker than or equal strength to the table itself. So the minimum would be ali but it would be cheaper to use steel.
A steel plate with 50x15 bars with 70x15 bars mounted on top to form the tee slots your require, and steel would be my preferred material.
Steel wont warp when wet/different humidity you would have to set your X & Y Axis to run parallel to the plate, now you might think this is a disadvantage not being able to machine the bed to suit the X & Y
But you can only get a flat surface this way if the material is thin as a very thick piece will show any misalignment.
Phil
-
17-12-2010 #53Whatever you are machining/clamping to the table has to be weaker than or equal strength to the table itself
-
17-12-2010 #54
Surely it all depends on what size cutter / feedrate I'm using - if the cutting forces are not to high etc. I was thinking more using the T slots for clamping wood, and using them to clamp my large milling vice (6" jaw, opens up to about the same) to the table for when I want to machine metals. That's still limiting me to only relatively small bits of metal though. If I want to machine a big sheet of aluminium then it's not going to be more than 8mm thick (cost again), so a 6mm cutter would suffice. What's the cutting force on a 6mm end-mill on aluminium at a decent feedrate? Surely not so much that lots of clamps on MDF won't hold it?
I agree putting steel strips on the bed is a good plan, but again very expensive - unless you know of a better supplier than me! I could skim the existing 18mm MDF bed with the router before putting the steel on top. That should get it reasonably parallel. I guess I could afford to make a smallish steel bed.
(Sorry I probably could have made this post a bit less rambling, I'm just thinking aloud.)
-
17-12-2010 #55
Could stick with a worm drive and compensate for the backlash on that, either in software or use a split wormwheel sprung to eliminate backlash. If you've got 3nm holding torque then clearly that gets 150Nm at that ratio. So say maximum radius of 75mm, that gets you up to 2kN cutting force ... plenty.
Yes, double sided tape is great for holding some things, especially PCBs. Effectively I would have 54mm of MDF, with some slots in it...plenty to carry the weight of the job I should think. Could try and calculate the deflection. I'm worried more about if I could do the bolts up tight enough without crushing the MDF. If I put a thin sheet of steel under the top MDF layer that should solve that.
Dad's still making legs for router - wooden frames are always his department. Going to go and help now...
-
The Following User Says Thank You to Jonathan For This Useful Post:
-
17-12-2010 #56
Sorry, I had not read the whole thread, I assumed that with a bed of the size you have, you would be machining wood etc. Phil, there are plenty of machines out there using an MDF surface, the MechMate springs to mind and that is one serious machine!! Others use the threaded inserts in the lower board and epoxy to secure them with a drilled replaceable spoil board above. However I guess to machine metals you will be using some form of coolant in which case MDF is a total NO NO.
Tim G-C
“I disapprove of what you say, but I will defend to the death your right to say it.”
(attrib. Voltaire but written by Evelyn Beatrice Hall "The Friends of Voltaire" 1906)
-
17-12-2010 #57
The point is, this type of clamping just will not work for a machine vice 4th Axis etc.
The Tee Slot nut will just pull straight out through the MDF or you only clamp with finger pressure:rofl:
Phil
-
17-12-2010 #58
Double Post
-
17-12-2010 #59
-
17-12-2010 #60
Thread Information
Users Browsing this Thread
There are currently 8 users browsing this thread. (0 members and 8 guests)
Similar Threads
-
NEW MEMBER: new member building a cnc router
By steeplejack in forum New Member IntroductionsReplies: 1Last Post: 11-10-2017, 05:07 AM -
Best all round mill/router? Vertical mill or gantry router?
By Richard in forum Machine DiscussionReplies: 2Last Post: 18-02-2014, 04:18 PM -
Building a hybrid CNC mill. Need advice and recommendations
By oldmam4m80s in forum Milling Machines, Builds & ConversionsReplies: 8Last Post: 16-08-2013, 07:11 AM -
My first 700 x 500 x 300 Mill/Router machine
By Lovre in forum Gantry/Router Machines & BuildingReplies: 16Last Post: 09-02-2013, 09:28 PM -
FOR SALE: CNC Router/Mill
By cimbian in forum Items For SaleReplies: 19Last Post: 25-09-2012, 01:10 PM
Bookmarks