By continuing to use this site, you agree to our use of cookies. Find out more

Member postings for Bob McDougall

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

Thread: Jig borer CNC conversion
24/08/2019 22:33:44

A frequent question is " how big steppers do I need". Well I need bigger ones. Quick test with GRBL Plotter. These moved a bit but it was clear they became out of sync and stopped altogether often. Current ones are Nema17 42mm body 0.45Nm .So I've ordered Nema23 56mm long 2.8A 1.26Nm . I could have added a gear reduction and used the origional ones but I want Z speed for nameplate and 3D map cuts and the pinions and pulleys would have been almost as much as the motors, £30 a pair for the 23 size. Will need to take it all apart and re-work. I hate having to take the ballnuts off the ballscrews but Im getting better at it.

Thread: Simple table of potential hardness of metals
22/08/2019 23:11:26
Posted by SillyOldDuffer on 22/08/2019 14:30:36:

Ifs and buts off the scale on this question because there are so many variables. Roughly though, and with many overlaps, softest first:

Lead
Tin
Copper
Aluminium
Magnesium
Dead mild steel (Car Bodies)
Black Mild Steel (Holding up buildings)
Cast Iron (varies)
Soft Brass (plumbing)
Hard Brass (cartridges)
Medium Carbon Steels (stronger than mild-steel, not so easy to work)
High Carbon Steels (Files and Razors, heat treatment essential)
Ultra-high Carbon Steels (punches)
Alloy steels, HSS, & camshafts etc
Tungsten


Hardness is a bit like Easter though - it moves about! Try stretching a length of solid copper core from a mains cable. Starts soft, then goes hard. Many materials can be softened by heat - annealing. Some, especially the high-carbon steels, can be hardened by heating and rapidly cooling - quenching. Metals like bronze and stainless steel work harden. Some types of stainless are vicious, going from usable to glass hard the instant a cutting tool is allowed to rub.

Hardness isn't the whole story. Though soft, pure aluminium is nasty to work with because it's sticky and highly likely to weld itself to a tool's cutting edge. Quenching steel for maximum hardness is rarely done because the process leaves the steel brittle to the point it can shatter like glass. Balancing Heat treatment for hardness versus toughness can be rather complicated. O1 (aka Gauge Plate) and W1 are favoured in workshops because they are easy to heat treat. O1 is designed to be quenched in oil, a slow process that strikes a good balance between hardness and toughness, as is needed in knife blades. W1 (aka silver steel) is designed to be quenched in water without cracking. The result is a bit harder for making drills, punches, and screw-taps, and it often benefits from being tempered (cooked in an oven) to reduce brittleness. The two alloys are similar.

When buying metal look for mention of machinability in the description. Many alloys are tuned to make them more suitable for turning and drilling etc. and life is made easier by buying them. Ordinary mild-steel is neither awful nor nice to machine but it's well worth spending a little extra on EN1APb, aka EN1A Leaded, or 230M07PB. Most Brasses machine well, but the Bronzes can be a pig, especially Phosphor Bronze.

Dave

Edited By SillyOldDuffer on 22/08/2019 14:31:02

I have been looking for a way to describe hardness to young engineers , we have Vickers, Rockwell, firth and brinell, I add mohs and shore. "The nice thing about standards is there are so many to chose from".

Thread: Jig borer CNC conversion
22/08/2019 22:44:11

fit new z drivenew Z underside

Just added the Z axis mechanics to my Lovely Downham mini Jig borer. all the pics for the Z axis manual removal are in my album. I didn't record the X and Y conversions as they were relativley straight forward. The dismanteling may be of interest .

everything removed

Was all going well until I got stuck with , how the hell does this bit come apart. Oh thats not a hole its a slotted spring pin. I'll post some pics of the X and Y tomorrow. Hopefully the pics are self explanatory. The new Z uses 12mm ballscrews each side of the spindle, NEMA17 x 40mm, 2A. The fixed end is made from two 10x28x8 deep groove bearings with a 0.2mm spacer between the outer rim so when the ballscrew is tightened it pulls the middles together to reduce backlash. they are sunk 10mm into the 12mm aluminium plates. Used solid 5-8mm coupling on the motor and the thin 3mm threaded bar can give for misalignment. I might put a shroud around them as they are vunerable. Had to unscrew both ballnuts fully off the screws for installation. sleves to hold the balls in but still lost one ball. 9.6mm OD 8mm ID sleve.

Edited By Bob McDougall on 22/08/2019 22:45:37

Thread: ward 2A lathe
09/03/2019 00:51:00

Hi David, yes we are looking at all options, what we are unsure about is just what acuracy is needed in the capstan head. clearly this machine was used to the point when we now have it so it was making parts even with this wear so if we can gain 90% of the origional acurracy . is that good enough. ?

What is the effect of a low center height capstan head ?

my thoughts are ,a centre drill will cut an off centre hole.

a drill will cut a taper

If we know these faults can we compensate for them ?

any hole over drill size is cut by the borijng tool so no problem

small drills will bend to adapt to the centre drill hole.

???

07/03/2019 23:59:10

Wear on the auxilliary Capstan slide has become apparent! . a centre drill is about 30 tho below centre. . The majority of the wear is on the lower section but the upper capstan slider has some signs of wear also. The wear appears to be front heavy so the whole capstan carrige is tilted forward and lower. img_0180.jpg

the wear from where the gibb strip was located to the moving upper capstan section.

img_0182.jpg

also wear of the capstan head into the capstan saddle.

img_0185.jpg

on bothe sides

img_0184.jpg

ANY options appreciated.

our thoughts are, moglice or equivalent.

Scrape the capstan slider (top bit) flat , cut down the capstan saddle (bottom bit fixed to the bed) and moglice it. but we will still be down due to the turret wear. but we could shim the turret up as its wear appears even but not sure if it is because of the cutting direction you would expect more wear on the frontside ?

Anyone around SN16 would apperciate help. we have got this far but we are not precision engineers.

Have purchased a surface plate and 1" wide cast iron bar to make a straight edge and will run a dial indicator over all the parts we can to get an idea of wear. next post might be in scraping.lol.

19/10/2018 23:10:35

three screws, not sure this is the right post.

Latest problem is the capstan slide is so worn it sits low centre height by about 1mm. so thinking of shimming the whole capstan head rather than the slide.

12/10/2018 22:31:28

Found an assembly error on the capstan feed that makes the feed jam. There is an arm inside the capstan saddle that engages with the capstan turret lower sprocket to push the head to its nest location. There is a button which can move this lever out of position so the turret doesnt auto turn when you move the mechanism back. This lever has an underside peg which needs to be on the INSIDE of the flanged button rod. we assembled it on the outside and it worked for a while then jammed. Image 1 is the outside button, image 2 is the lever in its incorrect position outside the plunger head. it should be on the inside. .

After we fixed it we drilled 1 inch holes in 5mm steel plate with no pilot drill. Nice.

capstan feed lever

Thread: All things Beaver Mill
14/07/2018 23:09:46

Hi Peter_H, glad your Bever is coming together. Yes the top bearing on the spindle was a common ball race , only the lower two were angled. Although there are different angles you can buy, I guess the larger the angle helps if you cut more drilling than side to side milling ??? I use fusion 360 CAD which has a free version for non commertial use and can also make stl files for 3D printers.

Thread: ward 2A lathe
07/07/2018 01:08:31

New brake pads fitted by Villiers Services in Birmingham . nice job £19.50. img_1274.jpg

re fitting the drum . should have been easy........

first fit. the cam arm was in the wrong position.

second fit , the cam arm was in the wrong position.

at this point we realised the cam arm was on a spline that had moved during the origional dissasembly.

what we thought was a 10 minute job is now next weeks job. She is hard mistress.

 

 

 

Edited By Bob McDougall on 07/07/2018 01:11:03

Thread: All things Beaver Mill
07/07/2018 00:58:34

Hi Peter, I replaced the spindle bearings deep side in . but as you say there is very little confirmed data about the correct method. The upper bearing was a straight ball with no tilt . I have since sold the beaver as it was too large for me and bought a Downham mini jig borer for light precision milling. hope that helps.

Thread: ward 2A lathe
08/06/2018 22:53:34

Home straight, just the Brake on the opposite end of the headstock from the chuck to look at, removing three deep grub screws holding the outer housing to the inner shaft reveals the brake shoe levers and the cam at the top. There's plenty of shoe left on one lever. img_1199.jpg

img_1202.jpg

img_1204.jpg

One missing shoe, and the three screws ! holding it in.

02/06/2018 00:13:25

So now we have a very solid 1950's lathe . BUT I want CNC, at least DRO , I used to have a Harrison L5 with screw cutting, This machine is very different and has no topslide but with CNC we only need the saddle and cross-slide as long as they are solid. So It will be a while but the next plan is to CNC it. Its a way of making it a 21st century machine. not just a part of history.

First I need to CNC my Downham mini borer which is amazingly better than i expected for milling steel with cheap Chinese cutters. I should get some carbine.

Before that we are cleaning up a Smart and Brown L4 capstan lathe to sell for funds for the great Dorset steam fair.

went on the mill at work today and used the DRO to cut 10 holes at 20mm spacing. didn't know dro's could do that.

04/05/2018 23:22:53

img_1265.jpg

Cutting a lead weight for my Lehman seismometer. . The oil pump still only feeds a drip onto the clutches . I recut the piston on my myford and overcut it, doh! , not as bad as the first time, but by 0.1mm dia. and it still doesnt really pump fully. we will ream the cylinder and take more care next time. The pump CAM also has a rim on it so might be worn so not really pumping to full capability. The cam is on a tapered spline so options are to replace whole or build up from weld and regrind. Once the gearbox is at full speed the oil splashes pretty freely anyway.

img_1251.jpg

The tin cast lead weight in the Jacobs 3 Jaw chuck with new jaws, not shamfer cut for small bars.

img_1266.jpg

Parting it off obviously too fast, it melted the lead and ripped it from the jaws.

But tonight we ran the lathe through all combinations of clutches and gearbox settings. fast forward, fast reverse, slow forward, slow reverse. for all three gearbox settings. and it behaved beautifully.

The oil feed is still a concern .

BUT now we can move on from input to reward ! . what can it do for us !!!

well we need tooling. , the Turret has 1" holes with a larger diameter recess I assume is the tolerance part. we have two kinds of turret fixings. only one has a boss that engages with the recess in the turret .

img_1267.jpg

Does anyone know the name of this fixture, with the boss. we would like to put morse taper 2 and 3 drills in, live centres, etc. .

Bill asked me if we has spent £1000 8 months ago could we have bought a machine that has the same capability as this one. well yes a colchester , ect.ect. but we would not be where we are today ,And with DRO and CNC and a new cross slide this machine can do anything we want .It might cost £1000 to add those things but we will have a one hell of a machine. And our machine might have made spitfires.

04/05/2018 00:55:57
Posted by colin brannigan on 28/04/2018 09:57:45:

To adjust the clutch the gearbox has to rebuilt and ready to run, it's a simple case of withdrawing the plunger and turning the adjusting ring as if tightening a nut, return the plunger to fit in nearest hole then move the clutch lever to engage the clutch, if there is no click as it engages the clutch then its too slack, if the lever wont engage the clutch its too tight. You will soon understand it when you try. Have to go out now but will return later if you have any questions.

Thanks Colin, Michael, Stuart, Its been a labour of love. Bill and I have been working on this every Friday evening. After last Friday we thought the clutches were worn but on Saturday morning I filed down the clutch lever pins so they no longer caught on the plates and re-assembled, adjusted all the clutches, the forward reverse first which were on the input shaft. and then the fast slow and I finally got full functionality. It was a Eurika moment.

The oil pump still needs a new plunger, but basically its working , a beautiful moment. I drank several beers. I put a 2inch brass bar in the newly discovered 3 jaw chuck and cut 1/8 inch cuts. the belts on the motor were slipping as we had only put two belts on. It spat chips about 5 feet across the floor. Heven. happy days.

I used to have a Harrison L5 which was a fantastic machine so to get some similar functionality I thought of putting a cross slide onto the ward. and with a DRO there is not much it couldn't do. Thank you all for your comments and support.

27/04/2018 22:59:03

The parts all back together we started her up with the two top inspection plates of the gearbox open to watch the four clutches in action. A few adjustments . and a few more. The forward clutch was at one adjustment tight and at the next notch not engaging. . .... strip it back down !img_1229.jpg

It seemed like the clutch plates might be worn ? it was the forward clutch .

img_1230.jpg

The clutch plates are compressed by three hooked levers , two visible above they compress the first black ring which should slide back when the levers are open but the ring was catching on the lever pins so not disengaging properly . When measured one was 1mm longer than the others.

img_1234.jpg

Would like to hear from anyone who knows how to adjust the clutches to the correct grip/slip. Not sure if the plates are supposed to have friction material on the surfaces , all these ones are absolutely smooth. Thought we had it running this week but no.

20/04/2018 23:42:23

WARD 2A CHUCK. It finally was found in the same shed the gearbox had been stored in. Covered in rust. img_1225.jpg

No makers marks. but it has very abused soft jaws marked as TEC JA6, THAME jaw JA06, for a Coventry /Tudor chuck. The chuck is 6 1/2" which makes it a TUDOR. serrations on the jaw 1/16 which is very slightly over the new metric 1.5mm. 10 teeth measured 15.8mm. 90 degree cut not modern 60. but as a consumable they were available and I had a new set of jaws in my hand this morning. Fantastic . img_1227.jpg

the backplate on the ward is a 5 1/4" with two sets of 120 degree fixings at slightly differnent diameters. The Tudor chuck pins into the outer set. but the 5 1/1/4 is the concentric seat. .

All going well and a happy week .

img_1228.jpg

Edited By Bob McDougall on 20/04/2018 23:43:57

20/04/2018 23:26:27

Thought I only needed two new levers but when testing the other clutch pair found I needed another three. Tangi-flow gave me a very good offer after discussion. So we started the re-assembly. stripped the input shaft to knock out the broken pin in one of the fixed barsimg_1211.jpg

img_1212.jpg

replaced the pin and re asssembled the clutch with new levers.

img_1213.jpg

put the clutch housing back on the shaft and pinned it in.

img_1214.jpg

put the clutch plates back on

img_1215.jpg

then put the levers back in. the new levers were tight on the pins so had to emery them out a bit to be free.

img_1217.jpg

the outer clutch adjustment ring assembly. ! we didnt know the function of this ring or the sprung pin until we looked at the gearbox cover. img_1224.jpg

JESUS! . since the dissasembly the cover had been upside down and we never saw this and had no idea what the sprung pins were for. it was only as i said, well why are there two access hatches in the gearbox cover we looked. The four clutch assembly was so alien we just thought the pins were to do with the clutch engaging automatically. But they are a manual means to adjust a screw thread to a locked position to allow for wear. Beautiful. img_1223.jpg

And the full gearbox gear and clutch system is re-assembled. I adjusted the four clutches with the sprung pins for bite and release. . lets see what happens under power !

12/04/2018 23:50:45

profile scanned the broken lever thanks to kind work colleauge .

profile scan.jpg

Thought I could get it water jet or wire erode cut but tangi-flow ward spares contact came through with origional spares.

2a arrangement of clutches.jpg

2a auto feed to turret.jpg

2a headstock gearing.jpg

2a sliding saddle and apron.jpg

06/04/2018 23:54:31

Further dismantling of the second clutch on the power input shaft, the sliding pin in the outer ring had sheared . The outer ring unscrews but the clutch doesnt come out over the middle . the taper pin must be knocked out and the clutch assembly pushed out from the shaft centre away from the woodruff key not over it.

img_1173.jpg

img_1174.jpg

broken lever arms and a sheared pin on the square bar fell out . img_1177.jpg

All replaceable. we were getting close!. just the end bearings to replace.

This end fell off whilst we were braying the other end. LOL.

img_1186.jpg

img_1187.jpg

img_1184.jpg

So this end bearing was inserted from the outside as opposed to the other end which was inside so the end cap just popped off. This had an externally removable cap that we could'nt get off in the vice so we re-assembled it into the gearbox housing to get best purchase then the cap gave in. The bearing was onto a groove so cant be pulled off without removing the double nuts. One end bearing was really chewed up and Im amazed it hadnt broken the cage. The bearings are 7/8 inner, 2 1/4 outer 11/16 . MS9, ordered 3 for £21.

The oil pump ! well half of it is missing. its not in the sump. The main body is there but the piston and spring are nowhere to be found. img_1189.jpg

img_1188.jpg

Not sure if this is the correct pump, the internals are there with the double ball bearing valves but the piston and spring are missing. Also there are two holes in the housing that dont hatch any fixings.

Does anyone remember the oil pump ?

30/03/2018 23:12:57

The oil pump runs off a cam (below) on the main input feed shaft the cam pushes a lever which rocks onto the oil pump via a shaft that was seized. So possibly in its past the oil pump seized then the clutch overheated and spat out a plate. The clicky worn bearings will be replaced and a new clutch plate (err.. ) made . local CNC shop will spit one out in a day. grit my teeth and pay. img_1143.jpg

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Warco
Meridienne oct 2019
Eccentric July 5 2018
Eccentric Engineering
ChesterUK
Ausee.com.au
TRANSWAVE Converters
cowbells
Allendale Electronics
emcomachinetools
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest