Author Topic: Learners Project - Simple Grinding Rest  (Read 4836 times)

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #15 on: May 14, 2017, 04:43:22 AM »
The results of all that swarf - Some blanks all nicely machined to size ready to be blued and marked out. 
James
Wellington - NZ

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #16 on: May 15, 2017, 08:57:39 AM »
So the working week has started so just small steps over the next few days.  Got a couple of parts done tonight.  The two parts that form the vertical adjustment have been milled.  There is one lathe operation left to do but until I get the plastic ball delivered then no mad rush to do that.

Pic 1 & 2:
Chain drilling before finishing the slot with a 6mm carbide 4 flute end mill.

Pic 3:
The two parts side by side just to show I'm really making chips and not just doing model renders.   :naughty:
« Last Edit: May 15, 2017, 09:01:41 AM by Joco »
James
Wellington - NZ

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #17 on: May 20, 2017, 07:32:53 AM »
Today was spent largely on another project needed to tidy up the mess of metal in the garage.  However after lots of TIG welding and a nearly equal amount of  :Mad:  :cussing:  :rant:   :wallbang:  :cussing:  :Mad: I hung up the TIG torch and played with the mill.

The result being I managed to get a couple more parts progressed.  The metal family is growing ... per pic #1.
James
Wellington - NZ

Online Kim

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Re: Learners Project - Simple Grinding Rest
« Reply #18 on: May 20, 2017, 03:35:58 PM »
Looking good, James!  You've got a growing family portrait there :)
Kim

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #19 on: May 21, 2017, 07:57:54 AM »
The end of weekend wrap-up ...
I was all gungho to do the dovetails thinking I could use an angle plate set in my vice at the correct milling angle then clamping the parts to this against a fence for reference.  The fence idea being that I could get one part all correctly aligned, clamp some steel as a fence on its base so I could mount the other parts for dovetailing in the same spot.

Anyway, it all came apart when I discovered the angle plate will not fit my vice.  Its 12mm to big.  So looks like I need to get a smaller one or come up with another method for accurately and repeatably mounting this stuff.

However no to be completely daunted I went on to do some other needed operations, some that needed to be done before putting angles on things.   So ... drilled and tapped some M5 holes and set up one of the risers that will clamp the 25mm plastic ball on the lathe faceplate (first time ever using this) and got the 30 degree chamber needed to clamp on the ball.

The pics ...

#1: Setting up the part and using a 6mm drill to help align the 6mm hole.  It wasn't perfect but for what it will be used for it should be fine.  Clamped this as best I could and given its not the most beautiful clamping job set about running at slow speeds (200rpm) and stopping between each cut to check everything was holding.

#2: The result.  While not the most polished lathe work it should do the job and to be honest a less than mirror finish on this clamping surface is probably a good thing.

#3: The M5 holes in all their glory.  These were drilled then power tapped on the mill at the slowest speed I have (60rpm).  Got to love gun taps.

#4: A little bit of a repeat but a nice closeup of the riser arm with the big 30 deg chamber at the top.

Cheers,
James.
James
Wellington - NZ

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #20 on: May 28, 2017, 11:36:55 AM »
A two part update to deal with the limit of 8 pics per post.

First off was setting up an angle plate with a reference fence to allow for the two outer dovetail blocks to be created exactly the same.

Pic 1a:  Setting the angle.

Pic 1b:  A pic to give a clearer view of the little fence I made to allow repeat setting of the blanks for the outside dovetail blocks.  I will also use the same setup with no movement for doing the inner dovetail block.

James
Wellington - NZ

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #21 on: May 28, 2017, 11:47:24 AM »
Part 2.

Getting the first part all clamped up and ready for milling.   Since the angle plate is a little "in the air" I am taking small nibbles from the top using a 10mm carbide end-mill at 0.3mm per cut to get rid of about 5mm then a final 0.1mm finishing pass to get to size.

So ... the pics    :popcorn:

Pic 2 & 3:
Showing the clamp up using my toolmaker clamps.  These are starting to prove to be very useful little items.  I am going to need to make some more of these.

Pic 5 (pic 4 removed as redundant):
The cutting in flight, a nice little pile of swarf appearing.

Pic 6:
The cut all finished in the clamp setup.

Pic 7:
The two outer dovetail blocks finished up.

Pic 8:
The two parts "nose to nose"  and looking nice an symmetrical.  But just how good was the setup for repeatability?

Pic 9:
The two parts on a flat surface with 60 degree faces matched up to see how tight a fit they are ... don't know about you but these look pretty dang good  for something straight off a mill to me.
James
Wellington - NZ

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #22 on: May 29, 2017, 11:27:54 AM »
The final part of the dovetails components is the sliding center piece.  This part will have the plastic ball attached which will form the main pivot point for the rest.
On the whole the fit between the parts is pretty close and things slide very smoothly.  Which is important as the recommendation is to NOT lubricate the dovetails due to all the grinding dust they is going to be about.

Pics attached.
« Last Edit: May 29, 2017, 11:31:11 AM by Joco »
James
Wellington - NZ

Online Kim

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Re: Learners Project - Simple Grinding Rest
« Reply #23 on: May 29, 2017, 05:26:19 PM »
Very nice looking dovetail there James, looks like it should do the trick for you!  :ThumbsUp:
Kim

Offline bruedney

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Re: Learners Project - Simple Grinding Rest
« Reply #24 on: May 29, 2017, 08:08:58 PM »
 :popcorn: :ThumbsUp: :pinkelephant: :whoohoo:
‘Results! Why man, I have gotten a lot of results. I know several thousand things that won’t work.’ — Thomas Alva Edison

Online b.lindsey

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Re: Learners Project - Simple Grinding Rest
« Reply #25 on: May 30, 2017, 12:52:47 AM »
Lots of progress that I had missed over the last few days James. The parts are looking very nice though!!

Bill

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #26 on: June 01, 2017, 10:34:40 AM »
A small update since the garage is freezing tonight.

Completed the slot on the table top.  Pretty standard process of marking out the ends of the slot, chain drilling the slot then finishing it with a 6mm carbide end mill.

The picture shows the slot and the the dovetail parts placed in position on the underside of the grinding rest top.

James
Wellington - NZ

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #27 on: June 03, 2017, 07:49:09 AM »
Some progress today with getting the dovetail blocks mounted on the underside of the rests top. The rest top is 6mm mild steel nominal value, actual size being 5.9mm after cleaning off the mill scale.  The M3 threaded holes are drilled 5.3mm deep and then threaded using a bottom tap.  The challenge here (per Harold's build instructions) is to get good thread engagement with the bottom tap from the start so as to maximise the amount of usable thread.  With the shape of the tap it looks like effective thread depth is about 4.5mm to 4.8mm.

So to solve this problem make a simple tapping jig that contains an M3 tapped hole which the M3 tap goes through.  Clamp it to the work and use the fact that the M3 tap will fed down into the hole at the correct rate to ensure a positive threading start from the beginning.

So now for the pics, cose we all want pics right?     :popcorn:

Pic #1:
Shows the tapping jig and the Irwin tapping attachment I used to get a grip on the tap.  Given how thin the M3 tap is this is just turned by hand with no handle and that gives a really good feed for how much tension is on the wee tap.
In the background is the first stage of the process I am describing done with the back M3 screws in place.

Pic #2:
After referencing off the actual hole in the dovetail block the resulting hole drilled to 5.3mm depth and ready for tapping.

Pic #3 & 4:
The tapping jig mounted and ready to start.  You can see the nose of one toolmakers clamp used to hold things.  Really starting to love these wee clamps.  So useful.

Pic #5:
Moving on to the final hole and tapping operation pretty much done.  You can see the tapping oil around the hole.   The general approach was a drop of oil into the hole before putting the jig in place and some oil on the actual tap itself.

Pic #6:
The final product.  Dovetail blocks all mounted up and a nice clean sliding movement from the central block with the M6 screw protruding from it.

Cheers,
James.
James
Wellington - NZ

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #28 on: June 04, 2017, 09:00:52 AM »
A little more progress, a lot of learning and fixing some alignment issues on the lathe.

Today was doing the other half of the ball clamping system and after liking the result cleaning up the original clamping part to be a better finish.  I also started some of the threaded rods that adjust things. Learning to turn such small diameters (6mm turned down to 5mm) was ultimately successful but the threading using my Frost dies was a failure as the first 5mm just got chewed up until the rubbish dies started to bite properly.

I also discovered quite a bad taper was being turned on the lathe.  Some checks showed things were not very flat.  Out by between 0.3 to 0.6 degrees in left-to-right and front-to-back respectively.  This was resulting in a taper of over 0.1mm across a very short distance.   Some adjustments with the digital level and I got the taper down to 0.01mm.  The only way I will get things better is to start using some shims between the lathe and the bench top. I'm quite keen to try and get this as good as I can so time to get some aluminium drink cans and start making some shims.

Anyway on to the pics.   :popcorn:

Pic 1:
Shows the underside with the plastic ball mounted and the (to be replaced) threaded rods in place.  If nothing else it has acted as a proof on their function and I know exactly how to go about making them for the next crack.

Pic 2:
Shows the setup for the final ball clamping part.  I figure out a way to get it clamped and not move about plus using the boring bar gave me the reach I needed to avoid bolt heads.

Pic 3:
The original clamping part in place and cleaned up using this clamping style. You can see a few slimmer clamps that are the beginnings of a low profile clamping set.  There is also a lone mill-clamp on the edge which was needed to balance out the weight on the face plate.

Pic 4:
The two clamping parts and the dovetail with plastic ball mounted.

Pic 5:
Simple "dry" assembly to show how things will get clamped.  Still need to make the spacer that will go at the base of the shorter clamp.

Cheers,
J.
James
Wellington - NZ

Offline Joco

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Re: Learners Project - Simple Grinding Rest
« Reply #29 on: June 06, 2017, 10:26:40 AM »
I managed to borrow an nice HSS M5 button die from Bruce and decided to redo the last two threaded rods which had the nasty stripping of the  thread on the first 5mm or so of the thread.

So here a series of pics of the first one I re did.

Pic #1:
Setup of the 6mm stock with support to be turned down to 5mm.

Pic #2:
Turned down and ready for threading.

Pic #3:
And a threading we will go.

Pic #4:
And the results.   You can see the new part on the left.  Nice clean thread with a good start right from the beginning. The one of the right is the original and you can see how rubbish the first ~5mm is.  Stripped and just yuk.

Cheers,
James.
James
Wellington - NZ