Monday, February 27, 2012

Arrival: Epicycloidal Wheel Cutter & Book

Seem like I can't stop buying... My purchases from Ian T Cobb of UK has arrived.

The cutter is a P. P. Thornton 0.8 module epicycloidal tooth form cutter. It is rather expensive, at £67.50 excluding shipping. Thank God that the WR Smith's Skeleton Wall Clock requires only one type, otherwise, it'll cost too much for something that will wear from use.

The J. Malcolm Wild's book came recommended by 2 gentlemen; GeneK and Mr Cobb. From my initial flipping through, I like the book already. The illustrations and photos are very clear and the style of writing simple to read. Now I wish the book from George H. Thomas was written in similar manner...

I'm expecting more things to come in the mail in the next few weeks; another book on clock making (recommended by GeneK), some measuring and Morse Taper stuff from CTC Tools, and a iMach3 Pendent from VistaCNC with accessories.

Time to hit the bed. Long day tomorrow with appointment starting at 9.30am.


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Hemingway Set-Over Centre - The Base (Part 1)

I started off my Sunday morning redoing the dimensions of the Base of the Set-Over Centre using the bottom right corner of the workpiece as datum.  This was from the advice of the good folks over at MadModder forum.  The drawings from Hemingway have the location of all features relative to the centre 5/16" BSF tap hole, which I followed when fabricating the Slide.  Counting the number of turns on the dial is easier with the datum from the bottom right corner and I was moving the table in one direction, thus not having to worry too much about backlash.

The stock was cut almost to length on the bandsaw and trimmed to 3" as called out in the plan.  This is the 2nd time I'm hitting the exact dimension - a real boost of confident.  Wishing for more as I progress...

Redoing the drawings with the bottom right corner of the workpiece as datum.
The stock was held in the vise and carefully tapped down to ensure full contact on the parallels beneath.  The layout lines can be seen in the pic.  No punch mark this time as advised in the forum.
Measuring the tip of the Proxxon Edge Finder. It actually measures 0.2", kind of strange from Proxxon which has everything else in metric.
Finding the edge in Y axis.  The table was moved over by half of the tip of the Edge Finder to zero the spindle axis to the edge of the workpiece. X was next.
Centre drilling of the 5 holes for later operations.  This is the first time I centre drill all the holes before drilling.  I always like to centre drill and drill through each hole before moving to the next location to reduce the number of times I have to move the table (and save on counting...).
Drilling the holes using 1/4" drill.
A pair of machinist clamp was deployed as limits for the slot to be milled.  There are 2 slots in this part; one connecting the 2 holes on the right and the other, the last 2 holes on the left.  This will save me from having to count the number of turns I've made to focus on the job at hand.  I plan to make mill stops in the near future for all 3 axes to ease the process.
Begin milling the slot with a 1/4" slot drill (or 2 flute endmill as the American call it). I started with depth of 0.2mm per pass but went on to 0.5mm.
Slot done.  The 3/8" slot 1/4" deep was next.
A piece of scrap used as depth stop for the Z axis.  Wanted to use machinist clamp for this but I couldn't locate the other 2 pieces I bought.
Done! Time to test if the cap screw will fit.
Unfortunately not... The supplied 1/4" BSF cap screw's head measures slightly larger than 3/8" and the 3/8" slot drill from Sherline cut the slot at 0.372".  The 0.372" seems to be consistent with the slot I did in the Slide before widening.  I should be buying another one locally for further testing.

I left the setup alone when I ended the session.  A trip to Chan Man Lee is necessary to get a new piece of 3/8" slot drill and probably another 4 machinist clamps of the same size as the current ones.  I may have a problem using the machinist clamps as stops for the Y axis as I'll have to clamp on the dovetail.  This may deform the dovetail, which is aluminium.  Maybe my next project should be making proper stops for all the axes.  If anyone has a good set of drawings of mill stops for Sherline Mill, please share them with me.  Meanwhile, I look at JerryG's for the lathe.  The concept should be the same.

Till the next session, be blessed.

Monday, February 20, 2012

Hemingway Set-Over Centre - The Slide

The Set-Over Centre is the 2nd kit I bought from Hemingway Kit.  The first was the knurling tool which I've not the confident to start working on.  Maybe after a few simpler projects I'll start my attempt.

Like most of the little projects I did, I've the drawings drawn on my notebook as 3D models so that I can visualise how things fit together.  The raw materials were cleaned up and cut to size to prepare for marking.

Enough of writing.  Time for pics...

The Slide

I measure the thickness of the steel stock and realised that it is not the 3/8" as shown in the drawing. Same goes for the width, which is narrower than the 1" dimension given in the drawing. I supposed these are not critical.

Cleaning one side of the stock to use as reference.

Marking out the other end to mill stock to length. This was the maiden "scribe" by my brand new Mitutoyo Height Gage.

I can't be more than happy with what I see on the caliper. This is important to me as I've not been able to "hit the mark" on the mill since I started the hobby. Hoping to see more accurate work!

Marking out the holes and the area to be milled. I used the permanent marker as "layout fluid". Tried shipping in Dykem but my order was held in US and can't be shipped.
Need to improve on using the punch. Would the optical punch help? Tried correcting by "moving" the punch marks as shown in some YouTube vids - not much of an improvement.

I was wondering if I should use the edge to move to the centre mark but decided to try using the Mitutoyo Centre Finder. Not really sure of how to use it though. With the point in the punch mark, I adjusted the handwheels on both the horizontal axes till I feel the Centre Finder smooth at the moving part. Anyone can share how this is to be used?

Centre drill...

Drilling with 6.4mm drill for 5/16" BSF. Took quite a while to drill through. There was quite some vibration felt during the process, prompting me to reduce spindle speed and ease the feed.

Hole done. Not very round isn't it...

Tapping the hole. The spindle with a dead centre was used to start the thread.

Countersink used to deburr the threaded hole. Should I be doing this before tapping?After finishing with the centre hole, I moved along X axis on both side of it for the 2 1/4" BSF tap holes. The 1/4" BSF tap doesn't have a hole at the end of its shank. So it went into the ER16 collet held in the spindle as guide.

The Z axis was lowered while the tap was turned using a wrench on the collet chuck.

Thread done and tested with a 1/4" BSF cap screw that came with the kit. I don't have anything BSF at home to test the 5/16" BSF though. It is meant for the threaded end of the half centre.

The surface was then cleaned of chips and oil. I redid the layout of the recessed area as the dye of the marker was washed away by the cutting oil.

I was a little nervous when milling the recess. My last work in steel making the flycutter was quite a painful one; the Sherline mill vibrated like no tomorrow and it was really loud!

It wasn't that bad this round. Each pass was only 0.2mm deep. After reaching the final depth of the recess (1/16"), the slot mill was moved to open up the slot above and below the centre line at full depth but with rather slow feed and speed. Conventional milling was used.

The recess completed. I measured the slots and found that I've one end at 15mm while the other end is at the correct width of 15.08mm. Is my horizontal axes not perpendicular to each other? Also, I went 0.07mm to deep though I dialed in the correct amount. I'll do the adjustments when making the Base.

The top was drilled and tapped for 2BA setscrew, right to the 5/16" thread hole.

The setscrew installed. You can see that it is not exactly at the centre of the 5/16" thread hole. Don't think this will cause problem.

The Slide is now completed. I may not want to mill the radius at the 2 ends of both the Slide and Base to simplify the build. Maye I should, to learn how this should be done.

I'll work on the Base in my next session in the shop.  One question which I would like to ask.  The 2MT arbor needs to be machined and thread 5/16" BSF.  I'm scratching my head thinking through how I should be holding the arbor.  The Proxxon lathe has a 3MT in the spindle.  My Sherline lathe has 1MT.  Do I hold it between centre?

Sunday, February 19, 2012

Mitutoyo Height Gage

The Taiwanese height gage I have has been giving me problem with its erratic readings. I stripped it apart a few times to clean up whatever I could find that appear foreign and it'll work for that session in the shop. In the next session, it went crazy again. This prompted me to search for a more reliable brand with a price tag that won't hurt too much. The search landed on the Mitutoyo 570-312. Next was to find out if it's available in SG. Mike had me call Region Supplies, which quoted me $628+GST. Mike found another source at much lower price (slightly more than $100 cheaper) but its waiting time of 4 months is a little too long for me. When I was at Chan Man Lee last week, I brought this up to Ah Hoe and he immediate gave Region Supplies a call. He was quoted $561+GST. I jumped in after talking to Mike.

The huge box the gage came in sitting on an empty table in my office.

The box was rather well padded to protect the gage.

I didn't expect it to be bigger than the Taiwanese gage.

In fact, it is taller by quite a bit. I like the large handwheel for height adjustment. It turns rather smoothly. I've to also admit that was attracted to this model because of its colour. It is a 12"/300mm, digimatic absolute gage with 0.0005"/0.01mm resolution and accuracy of 0.0015"/0.03mm.

Standing it to the lathe. I used it (with the brown paper removed of course) to measure the tool height from the bed and compound slide. The large base stood steadily on the bed when I was doing the measuring.

It is now standing on its home, which is the granite surface plate. I actually prefer something smaller like a 6" version but the 12" is the smallest they have.

It'll be put into actual when I mark out the slider of the Set-Over Centre.

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Thursday, February 16, 2012

I found this in SG!!!

Didn't expect to see this! I had an appointment around Arab Street earlier today. Was a little early do went walking around a very old mall of sort. I saw this old shop selling wall clocks and spotted a skeleton clock. Went in and asked if it is for sale. 5 min's later, I walked out with the clock without the wooden case.

This is it:

I'll take more pics when I get home.

So much for now.

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Saturday, February 11, 2012

A Trip to Chan Man Lee

I'm planning the building of the Set-Over Centre from the kit I bought from Hemingway Kit in UK. This tool allows tapers to be cut by offsetting its half dead centre at the tailstock end. Good for my type of tailstock, which is fixed.

Provided in the kit are some steel pieces, a MT2 taper, 2BA, and BSF screws. Given my limited experience and skill, I'll be following the plan as close as I can. That started the hunt for BA & BSF taps & die.

The kit came in 3 bubble wrapped of steel stocks, fasteners, MT2 arbor, construction notes and drawings in a clear plastic pocket.

The content being laid out.

Prior to going down to CML today, I searched at hardware shops in the neighborhood. None of them sell these type of taps & dies, only metric & some imperial type are available. While at the mechanic's, I called up CML and was told that they've the whole range.

Good service, as usual, was encountered at the shop. Had a good chat with the guy by the name of "Ah Hoe" (hope I got his name right). Left the shop after 1/2 hour with a box of stuff of almost SGD200.

The content of the box: 2BA tap & split die, 5/16" BSF tap & split die, die holder for 2BA, 5.1mm & 6.4mm dia drills (1 of each), 7mm dia 2 & 4 flute endmills (1 of each), 1/2" Jacobs chuck & MT2 arbor, cutting oil for steel.

Before I start my build, I'll be reading the construction notes a few more times and visualize the process of manufacturing the tool in my mind.

That's all for today. Have a blessed Saturday.

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Trying out new way of work holding in the lathe

My children will be going away with their grandparents to Malaysia tomorrow.  Their mother will be having appointments from the morning till just before Mandarin Service at 5pm.  Most importantly, I don't think its a good idea for me to be home alone with just the our helper.  Not that I don't trust myself but I don't want any possibility of any false accusation should she be unhappy about things or is missing home.  Anyway, there goes my plan to have a good 1/2 day in the shop making the ball bearing thrust collar for the X axis.  I'll be going with her for her appointments (as her chauffeur of course...), bring the car to the mechanic to check the strange sound while accelerating from stop, and to pick her mom up for church.  If time permits, I would like to drop by the metal shop to pick up some brass plate and free machining steel for some projects I've in mind.

Though feeling a little tired, I spent some time in the shop trying out a way I saw on MadModder on holding a thin piece of round stock in the lathe to machine the round surface.  I've never tried that before though I saw some pics on some blogs/website of it being done.  The thread Ross started on his oscillating steam engine build can be seen here:  He was making the flywheel and holding it in the chuck jaws will not allow the cylindrical surface to be turned.  A big washer with insulation tape covered evenly was used between one face of the flywheel and the closed chuck jaws and the other face held by the revolving centre on its centre drilled hole.  Driving by friction, he was able to turned the surface down to the required OD.

I was wondering how I can turn the OD of the 15mm thick aluminium round stock down to 39mm diameter with the jaw gripping the OD.  For the Y axis, the stock was 40mm long, providing a portion of the stock to be held in the chuck jaws.  Now that I'm left with 15mm after the completion of the Y axis thrust collar, I'm unable to do the same.  Ross' way of doing it may just work for me.

Changing the carbide insert to HSS.  I bought this some time ago from AR Warner through LMS.
Facing off to clean up the part.
Centre drilling the face to put a 60 degree hole for the revolving centre to bear against.
Sticking insulation tape on the chuck jaws.  This may be where this setup fail... I didn't use a washer to provide sufficient surface area.
The revolving centre bearing down on the stock in the centre drilled hole. Some pressure was applied before locking the tailstock spindle in place.
Light cuts were taken at around 0.05mm per pass.  Nice...
The stock start to shift out of position as I was just about 0.6mm away from the diameter I want.

I took the piece out trying to think of a solution.  Then I remembered seeing someone on the web using a bolt through the centre hole drilled in the stock.  I rampage through my drawer of hardware to find a bolt of right size for the job.  Found a small bag of bolts of 3/8" with washers and nuts.  I quickly encountered the next problem - how do I drill the hole in the middle of the stock when I know that I will definitely hit the chuck jaws as the drill exits from the back of the stock?  at 39.6mm diameter, the jaws were in its reverse direction.  The step on each jaw gives very little room for me to clamp down the stock and no room for me to insert a piece of parallel to do that.  So, over to the mill I go.

The spindle was centered using the centre drill hole with the MT1 dead centre.  This don't have to be very accurate as I still need to drill and bore the centre hole for the bearings.
After drilling through with a 6.5mm drill, I took out the 3/8" drill to enlarge the hole for the bolt. But the drill is too long to be used on the 5410...
Found another bag of bolts and nuts that are smaller than 3/8" (can't remember the size. Sorry...).  The drill for this bearly clear the stock.  Anyway, managed to drill out the hole I need.
Test fit with the bolt. Just a slight wiggling room can be felt.  This should work.
Fastening down the stock in the bolt.
And into the lathe it went...
From the side.
I pat myself on the back for this part of the job done.
And a big smile when I measured the OD!

Its now passed 3am.  I've to leave the boring of the bearing mounting hole and the 2 recesses for the flange till the next session.  Don't want to be sleeping on the job tomorrow, especially at the wheel.  Time to wash up and hit the bed.