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Member postings for Neil Lickfold

Here is a list of all the postings Neil Lickfold has made in our forums. Click on a thread name to jump to the thread.

Thread: Lathe Erratic Surface Finish
03/05/2020 06:34:22

Some materials are difficult to get a good finish on. Sometimes having the surface shiny may actually be a worse actual surface finish than one that looks dull but has no tearing. In general , a depth of cut of 1/4 the radius of the tool ,and a feedrate of 1/4 to 1/8 feedrate. So with a 0.4 radius tool, a 0.1mm depth of cut (0.2mm diameter) and a feed rate of 0.1mm to 0.05mm per rev .Sometimes an oil can help improve the surface finish, sometimes a soluble coolant can help as well.

Thread: Mill Wobble
22/04/2020 20:14:15

Use a marker pen, on the outside of the spindle. Mark where the high side is and the low side and 1/2 way between. Now keep rotating, to see if it is consistently high on the high side and low on the low side. If it is, then the bearing is unlikely the cause. You can tilt the head over, and reskim the inner taper of the spindle to get it true on the front taper. If you snug the gibs and raise and lower the column, should be able to make it as round as the concentricity of the spindle bearings. The more difficult part to test is the concentricity of the parallel register, further up inside the spindle. If that has a run out of 0.02mm, that error will show about 75mm below the spindle .

Neil

Thread: Grinding rubber
14/04/2020 07:44:22

You need to dress the mounted point with a sharp diamond, not a dressing stick. Looks like I did not mention that important part. Sorry. You can easily see if the wheel is dressed sharply or not,by just putting a scrap piece of the material to be ground, against the wheel, or mounted point.

Neil

12/04/2020 21:53:16

I grind cork and rubber with a Dremel on my lathe. I use the hand extension and made a simple clamp to hold it .I use the sanding drums, 120 grit or 80 grit for a fine finish, and the 40 or 60 grit for the roughing. I use a vacuum cleaner hose very close to the set up , mainly to suck away any rubber off the sanding drum, to reduce it from being blocked. This turned out to be quite important and keeps it all cool as well. The fine grades, need to be very sharp, and for my set up, they do not take a lot of volume of material . The course grade will take away a very large volume of material. I did make some 38mm drums that screwed onto the handpiece, and used the pre adhesive commercial sanding belt material. It worked very well. I quickly learnt why they have a spliced joint arrangement. Contact adhesive worked very well for using carborundum wet/dry paper. The carborundum paper in eiether the sanding drums, or on my 38mm drums, worked the best of the various paper types available. For smaller holes in urathane, I use the cheap open structure mounted points. The white ones were best, but the pink ones also worked quite well, Use the coursest grit available. The course desic diamond wheels also work, but will block or clog quite easily. Using just some water with a small amount of dish wash water to break down it's water tension worked quite well. Small holes being around 3mm to 12mm ID.

Hope this helps some people out..

Neil

Thread: Will cash become obsolete ?
07/04/2020 08:10:12

Out here during this corona virus lockdown, places are not taking cash. Supermarkets are refusing to accept cash for the groceries. Cards or go hungry.

Thread: Four Jaw chuck
26/02/2020 09:32:09

To indicate stock accurately with the 4 jaw chuck, I like to use Aluminium or brass pads ,between the jaws and the work piece. These do 2 things, prevents damage to the work piece, and allows an area to squash up a little to allow you to get the very last little bit out of the alignment of the part. In general it should be quite easy to get a part indicated to 1 thou , especially when you pre dial with 2 short keys. Then use the main key for the final micro adjustment. Realise that some jobs , just require light cuts to get the best results over all.

Sometimes using 2 dial indicators can make the setting up of a part much quicker.

Neil

Thread: Cylinder bore measuring
22/02/2020 19:15:14

The 4 point ball comparator will show the error of a 3 lobed hole and a hole reamed with a standard reamer that is not round. Plus if careful you can use a micrometer or a slip stack to set the gauge with. The concept of the Russian style ball and pin style gauges, is that you can have differing arrangements of the ball orientation. The one I have, the pin slides in the assembly is quite a neat fit, but slides. The ball is also a very close fit to the mandrel. It works really well. Of course, there are many options to try and measure something, and what you are looking for will determine the type and style of bore comparator or bore micrometer being used. The more accurate you are trying to get, the more difficult it becomes to measure. The greatest difficulty is not the exact temp of the work environment, but the stability of that temp. To get back to a standard size, you can calculate how much bigger the item should measure from the standard of 20 deg C.

Thread: Myford ML7 headstock diameter
20/02/2020 06:01:24

less than 5/8 of an inch is how my S7 came, so most likely the 19/32. I have since made a 16 mm carbide tipped reamer and pushed that through the spindle. I did bore it first for the 1st 20 or so mm past the taper of the MT2 when the 10mm starts. I really should have made the reamer 16.2mm oe so to allow for metric bar. I can get 5/8 bar through no trouble, and straight slightly under sized 16mm bar bar stock at a push.

Neil L

Thread: Effect of Tensioning a Boring Bar
07/02/2020 10:23:23

I can't do the math, but liken it to a plastic bag tube. Put pressure in it, and it is substantially more rigid than when the pressure drops, etc

Sandvik did boring bars with oil and a piston. As it is being used, (in a lathe) you can adjust the pressure and tune it to the situation it is in. I have not made one yet, am thinking about using it to fix a bar and see what happens.

When I get it done, will post the results here. The bar I am going to try has a 12mm diameter shank and a min bore diameter of 14mm. It would be great to be able to do the math t hing and figure out that if it has 120psi it becomes this rigid for example.

Neil

Thread: Superglue chucks
28/01/2020 08:57:04

Sometimes freezing can remove super glues as well. Tap it with a piece of wood and hammer while still frozen.

It just takes longer unless you have dry ice handy.

Neil

 

Edited By Neil Lickfold on 28/01/2020 08:57:44

27/01/2020 07:42:44

It depends on the super glue being used. There are higher temp super glues that will hold to about 150 c or so, and others can only hold to 100c to 110c.

Thread: Reamer specifications ?
20/01/2020 09:14:27

You can buy a standard tolerance reamer, and carefully lap the OD to make the closer tolerance hole. The better reamers I find are the ones that have un even flute distribution. For accurate holes, I pre bore with a undersize reground end mill or I make a single point cutter that effectively will bore the hole in the correct position. Then ream.

For important hole sizing, I make a test hole and measure it. Then if needed, lap the od some more and re test again. I am finding that the hss reamers that are readily available out here from the tool merchants, are on the upper limit of the H7, rather than lower limit.

Different cutting fluids etc will vary slightly the result , and so will the cutting allowance etc. Castor oil can make a hole smaller than the reamer, but only by 2 to 4 um. But is not absolute guarantee though. Castor oil will allow oversized parts to assemble that would other wise be a press fit. Down side, castor oil makes an ugly mess over time.

Some places that make carbide reamers, will often ask for a size limit or the size you want with the maximum and minimum size. Like a Ø4.494mm reamer with an upper limit of Ø4.496mm , these will cost like 60 to 70 pounds each like the example I gave .

Thread: Myford super 7
14/01/2020 09:09:01

I always use the clutch, unless screw cutting a thread. I use the motor switch and leave the 1/2 nut engaged. Now that I have a programmable VFD, the start is softer and the stop is softer as well. Another advantage of the VFD is the ability to slow down the spindle before turning off, very helpful with the odd large work piece. With the clutch, you can also slowly engage or disengage on large work pieces.

Thread: Australian Bush Fires
14/01/2020 04:47:33

New Zealand has provided Wallabies in the past to help out their inbreeding problems. They are around the Rotorua area, and are a wild population with little predators. Maybe more will be sent latter in the year.

Thread: Making a superglue chuck adapter for brass wheel
26/12/2019 18:46:17

Super glue to hold thin parts has been around for a very long time, it was used in industry in 1982 when I started my apprenticeship. We made the mandrel from similar material to the part being made. we put the mandrel and part into the tempering oven set at 120c . the part seperated, and the mandrels soaked in acetone to clean off the glue and start again. So we had brass, steel and AL mandrels. Sometimes the mandrel was skimmed , depending on the setup. When cylindrical grinding, or surface grinding, it was important to have a fresh dressed sharp wheel that did not have too much width. The part needed to be cut as cool as possible.

I remember when we had some thin parts being made from Delrin, and it did not glue at all. So be careful when using the cyano holding method.

Neil

Thread: Lathe lighting
07/12/2019 19:14:57

At the back of the lathe is a little cabinet to put tools whatever on, and also is a splash guard of sorts.

I put in 2 rows of led strip , and after install , added a curved down piece, to keep the bright light out of my eyes. This gives very good light at the back side of the lathe and gets quite a lot of light down a bore to a certain extent. The led is covered with a plastic difuser. It keeps oil and chips off the strip and makes a more uniform looking light. I chose 4k led strip. 5k seemed too blue of a light for me. I also add some led strip light , directly above the lathe centre line, and one strip above , inline with the front edge of the lathe bed. So the over head strip pairs, are only about 60mm apart. The extra set was added, as the centre line light did not illuminate as well as I hoped for. Maybe if I had a higher density strip would have been better. The strip does produce some heat , so the next lot will be on the purpose made Ali extrusions, that come with a range of diffusers to select from. There is such a wide choice these days of lumins per meter as well for the led strip that is available as well. With mine it was ordered from over seas, and that was a mistake, as I had no idea of how many lumins per meter I really needed to have a good light spread. I was only looking at initial dollars , not the real technical stuff, that I would have got if I went to a local led specialist who would have solved a lot of issues, and in reality , was not that much more expensive, and I would not have waited 8 weeks for it to arrive.

Thread: Reamer size questions
02/12/2019 17:46:03

You can make a lap, and lap the od of the reamer smaller to get it to the diameter that you require. This works very well with machine/chucking reamers. Lapping a hand reamer does not work so well however.

Neil

Thread: Lathe boring tool - top rake?
19/11/2019 08:55:45

There are positive rake insert ranges, usually for Aluminium and plastics. They work well on Mild Steel and softer steels.

Thread: Undrilling a hole in brass?
18/11/2019 21:37:52

Another option would have been to have made a rivot. Made from the same material is almost impossible to see as well after being peened in place.

Thread: heat-treated S2 steel alloy - machining
10/11/2019 18:05:12

You can turn hardened S2 with ceramic turning inserts. Dry cutting is about 90m/min surface speed or 900rpm.

Depth of cut with a 0.4mm radius tool is 0.2mm so 0.4mm on diameter max depth, and a feed rate of 0.06mm per rev, or 2 thou per rev. So a very fine feedrate.

Seco make series TH1000 grade insert, in a few geometries , these will also cut hardened steel, but at 25 to 50 m/min, so 1/2 to 1/4 the surface speed of the ceramic inserts.

The above inserts are available to the TNMG16 tool holders, the triangle 6 edges, negative holders.

Neil

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