Author Topic: surface grindy type project (Read 41438 times)

shipto · « **on:** March 11, 2014, 06:37:40 PM »

Everything I want to do requires slides of some sort or another. I have made slide before by endless hours of lapping crude steel plates but this gets tiresome.
I have decided to have a go at a project which will hopefully make the process a little less tiresome and make a surface grinder, I am going into this with low expectations and the hope that it will at least make the lapping last hours rather than days.

I have started by concentrating on the X,Y movement for the moment, I already had a couple of 8mm bars salvaged from printers and some linear bearings to suit them which I brought a while back with the intention of making a reprap printer. so these where drilled and tapped for 5mm bolts each end to fit into the housing for the front to back travel. I would prefer something more robust but if this works well enough it may be able to make better for itself. I first made it with just a front and back but then thought that it might flex a little too much so made a square frame to hold it steadier.
I made some bearing holder blocks for the top of the runner, this will be a cantilever type setup.

Next I needed to make the lower runner bearing holders, they are slotted on the side to adjust the table for squareness I still need to make and attach the blocks to do this adjustment and lock it in place. 5th picture shows them attached to the underside of the table and 6th picture shows the table on the bar I am going to use for the runner.
Hopefully tomorrow after work I can sort out the adjusting blocks.

tom osselton · « **Reply #1 on:** March 11, 2014, 07:39:58 PM »

Should be a good build!

BaronJ · « **Reply #2 on:** March 12, 2014, 01:22:14 PM »

I hope that you are going to put some boots on those slides to protect them from dust and grit. If you don't the grit will play havoc with the smoothness of movement.

shipto · « **Reply #3 on:** March 12, 2014, 01:45:47 PM »

yep rubber wipers and brushes as well as guards to hopefully stop anything getting under the bearings.
Had a little time to spare at work today so made some parts for the frame pictures show the base and upright bits going out to shed after pointless to get the blocks done.
Done!

shipto · « **Reply #4 on:** March 14, 2014, 06:44:14 PM »

Got framework home and spent a little time in the workshop, I was sorting out the main runner plate. The picture shows the pilot drilled plate in place one the frame (sorry for the rubbish picture but I didnt have proper camera with me)
its will have 3 bolts pushing against the plate to get it lined up properly and 6 bolts to hold it to the frame and also eliminate any twist in the plate.

shipto · « **Reply #5 on:** March 15, 2014, 01:02:33 PM »

Loosely bolted together but not set up yet and I have to say I am very pleased with how smoothly the table glides along on this plate. Dont want to jinx it but maybe it will give good results after all.

shipto · « **Reply #6 on:** March 19, 2014, 04:06:38 PM »

I have been trying to work on the gears for the feed screw but forged ahead without a clear idea in mind about what i needed and as such I have worked myself into a corner.
I am now thinking its a scrap it and start again job, however the gearing I have found should (if I have done my maths properly) give me a little over 0.1mm per full turn of the handle I just hope this will be fine enough control.

awemawson · « **Reply #7 on:** March 19, 2014, 04:17:29 PM »

Many a grinder has two speed gearing, as the fine feed needed is a right royal pain if you need to move a significant distance while setting up. On my cylindrical and also my surface grinder you pull out a knob to engage a coarser feed. Perhaps you could incorporate something similar ?

shipto · « **Reply #8 on:** March 19, 2014, 04:44:10 PM »

Quote from: awemawson on March 19, 2014, 04:17:29 PM

Many a grinder has two speed gearing, as the fine feed needed is a right royal pain if you need to move a significant distance while setting up. On my cylindrical and also my surface grinder you pull out a knob to engage a coarser feed. Perhaps you could incorporate something similar ?

Its not a bad idea actually if I can figure out a way of driving the second stage of gearing direct then that would bring the travel to .5mm per turn and would certainly save a lot of handle turning.

SwarfnStuff · « **Reply #9 on:** March 20, 2014, 03:06:50 AM »

Not sure why you think it's a scrap and start again job as you didn't say. Or I didn't read carefully enough. From my looking at the last pic, if the gear plate attached to the lead screw is rotated 180deg it looks like it would line up close enough to allow fixing of the two plates so the gears mesh ok. Of course the way you have it may be what is needed for mounting. Good luck with whatever you decide - tis all a learning experience. Think of it a practice if it helps.
John B

tom osselton · « **Reply #10 on:** March 20, 2014, 11:28:50 PM »

Why don't you use a sliding gear that way you could have the fine feed and the more rapid travel?

shipto · « **Reply #11 on:** March 21, 2014, 08:19:47 AM »

Theres much I would like to do but I am working on a shoestring budget (otherwise I may as well just buy a old surface grinder) with salvaged parts for most of the project. The gears are out of angle grinders and a drill, the screw is from a van jack etc.

PekkaNF · « **Reply #12 on:** March 23, 2014, 06:21:56 AM »

My friend has a old surface grinder that the table traverse is done with a wire (cable?) no thicker that a moped/bike gear/brake cable. And it seem to work.

If you can find a worm gear for slow speed, such as windshied wiper motor to turn drum (for cable feed), fast manual set would be pretty easy if the cable is tightened with a spring. Just a geometrical lock against the spring load, like a tool box spring lock or such?

Pekka

shipto · « **Reply #13 on:** March 23, 2014, 04:17:04 PM »

Quote from: PekkaNF on March 23, 2014, 06:21:56 AM

My friend has a old surface grinder that the table traverse is done with a wire (cable?) no thicker that a moped/bike gear/brake cable. And it seem to work.

If you can find a worm gear for slow speed, such as windshied wiper motor to turn drum (for cable feed), fast manual set would be pretty easy if the cable is tightened with a spring. Just a geometrical lock against the spring load, like a tool box spring lock or such?

Pekka

Its not a bad idea however I have plans for the left-right back-forward movement of the table which will make it a set and forget machine. Definatly worth remembering for the future however

This weekend had a fair bit of time to spend in workshop working on the gearbox for the lowering and raising of the grinder posted a few pictures which will make sense once I complete the bits and put it together.

shipto · « **Reply #14 on:** March 25, 2014, 05:59:44 PM »

PekkaNF you have really done it now

I was merrily making this gearbox when I started to think about your comment and had a eurika moment followed by a

for not thinking about this before.
A much better way which would solve both the problems with feeding the grinder to the work and having a course feed for setting it close. If I can A) get hold of the correct tap for the screw I am using (possibly a 18X4 LH trapazoidal) and tap the center of a worm gear or B) turn the nut I already have and press it into a worm gear, I can lock the thread at the bottom to use the fine feed or let it free and turn the screw for the course feed, something like that shown in picture except the screw could be locked off rather than fixed.
I hope you get the idea of what I am thinking.

shipto · « **Reply #15 on:** March 29, 2014, 04:40:04 PM »

Made some good progress today (thanks mostly to the word NO! long story) anyway I started to set things up better than they were, the main runner plate is set as good as can be until I make a few cuts and see how it is grinding. started to weld the frame to the base but ran out of wire before I had finished tacking it so its still clamped for now until I get more wire.
Also started on the up/down for the grinder its just a simple slide using angle irons and a little bit of flat for a gib. It all seems to go together well. The gearing for the screw for this is well under way too but i forgot to take pics of just that so theres one job for tomorrow.

shipto · « **Reply #16 on:** March 30, 2014, 03:50:54 PM »

Progress

mattinker · « **Reply #17 on:** March 30, 2014, 04:21:57 PM »

I'm enjoying your shoestring Grindy thing!

Regards, Matthew.

shipto · « **Reply #18 on:** March 30, 2014, 05:00:46 PM »

I stopped short of calling it a surface grinder because I have seen some get quite elitist about them

PekkaNF · « **Reply #19 on:** April 02, 2014, 08:54:39 AM »

Quote from: shipto on March 25, 2014, 05:59:44 PM

PekkaNF you have really done it now

What I did now?

I mean I live for things like that.

Quote from: shipto on March 25, 2014, 05:59:44 PM

A much better way which would solve both the problems with feeding the grinder to the work and having a course feed for setting it close. If I can A) get hold of the correct tap for the screw I am using (possibly a 18X4 LH trapazoidal) and tap the center of a worm gear or B) turn the nut I already have and press it into a worm gear, I can lock the thread at the bottom to use the fine feed or let it free and turn the screw for the course feed, something like that shown in picture except the screw could be locked off rather than fixed.
I hope you get the idea of what I am thinking.

To tap trapezoidal is not very easy and taps are not exactly cheap. Also threading small ID trapezoidal thread is no fun. Buy the nut and make it do if you can.

I think got your idea....you want to do fast traverse by turing the screw, and (slow) feed by using worm drive. Nifty. You need brake/lock for the srew tough, but that should be pretty doable. Simplest form might be extra nut on the tapezoidal spindle to lock it imovable to the frame.

Pekka

shipto · « **Reply #20 on:** April 02, 2014, 04:54:28 PM »

Went with the altering the nut option in the end (see above) as wife couldnt get me the right sized tap it seems to be a special thread which are more expensive and harder to get hold of, no matter though its all going in the right directions now

As for locking the screw to use the fine feed I am simply going to have a locking bolt contacting directly with the screw it wont hurt if it chews it a little as it wont effect the feed.

shipto · « **Reply #21 on:** April 10, 2014, 05:31:41 PM »

what a week

car failed MOT last friday, which I expected but thought it would be too expensive to get through which it wasnt just cv boots, dodgy handbrake, drop links and a sidelight. do you think the bloody cv's would split from the shafts anyway what with that and helping a friend out with a pocket bike i didnt get much done to the project.
what I have done i havent taken pics of but I will get to it and I am pondering what to do about movement backwards and forwards. Side to side is easy I just dont know whats best for the other.
thoughts so far:
1)ratchet and pawl system turning a thread
2)very slow motor turning the thread (this would mean the piece would be moving in two directions while wheel is grinding might cause problems?)
3)stepper motor with either a thread or belt (a little bit more complicated but nothing the arduino couldnt handle)
opinions welcome

tom osselton · « **Reply #22 on:** April 10, 2014, 09:30:11 PM »

Why not just use a bike chain fastened to both ends and hooked up to a stepper to drive them back and forth the same motion as a printer. To advance the table at the end of travel (possibly setable) it could advance the gear 1 or x amounts of teeth.

shipto · « **Reply #23 on:** April 11, 2014, 11:55:37 AM »

Quote from: tom osselton on April 10, 2014, 09:30:11 PM

Why not just use a bike chain fastened to both ends and hooked up to a stepper to drive them back and forth the same motion as a printer. To advance the table at the end of travel (possibly setable) it could advance the gear 1 or x amounts of teeth.

If I choose the stepper motor route I will probably do this although maybe with a toothed belt rather than chain

PekkaNF · « **Reply #24 on:** April 12, 2014, 04:01:11 AM »

Traverse?

You may want to have a look on this project:
http://www.metallmodellbau.de/MINI_BONELLE_II.php

There are few pictures of omega drive type application halfway down the page:
http://www.metallmodellbau.de/pictures/MINI_BONELLE_II/MINI_BONELLE_II_504.JPG

Now, there is one thing you may want to consider, these relatively flexible drives are good for upphill or climb grinding as it happens on tool sharpening, but I would research and think to use this on surface grinding....analogous to up/down hill milling. You get by when you grind up, but on the return stroke you need very rigid grinder/drive or a ability to lift the grinding head during the return stroke. Maybe you have this already devised? I didn't fully follow all details.

Pekka

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Author Topic: surface grindy type project (Read 41438 times)