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Member postings for Bob Rodgerson

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

Thread: Broken tap in expensive unit!
13/09/2017 17:18:22

A Carbide drill will drill out the tap but it will be difficult to keep it on centre, especially with the surrounding material being brass. Welding onto the tap may melt the brass too. Acid may de-zincify the brass and leave it in a mess, not sure what Alum will do to brass, probably turn it a lovely shade of green.

Spark erosion might be the way to go but not sure if the article has to be submerged in fluid whilst the tap is being eroded.

Thread: What Did You Do Today (2017)
09/09/2017 23:46:37

I got round to fitting the Rapid Turn attachment to the milling table and set up my home made Gang tooling for it.

I am pleased that so rigid but unfortunately the front plate is to far outboard of the spindle axis to allow use of the QCTP from the Lathe as I run out of Y his travel. However I will probably be able to set the lathe off centre on the mill table sufficient to permit it's use. I suppose that will teach me to double check everything and measure up properly.

Here are some pictures with some as yet unfinished tool hangers attached.



It is difficult to get a decent picture but at the foot of the tool hanger on the bottom left is a profile tool in the middle a boring tool and on the right a parting tool.

There is more work to do on the hangers to accept parallel shank tooling such as drill chucks and ER 20 collets.

Thread: Newbi
08/09/2017 08:23:39

John, welcome to the hobby. The condition you describe is almost certain to happen whenever you turn a piece of work unless you have backed off the tool at the end of the cut as Chris has explained. You can also keep the setting but continue the cut back until the tool clears the end of the work because there is sure to be some spring in the metal that you are trying to turn.

With experience you will learn how many passes at the same depth of cut are required to take all of the spring out of the work. It also depends on how sharp the cutting tool is and how close to centre height that it is set.

Lots of practice will get you there.

Thread: The Workshop Progress Thread (2017)
08/09/2017 00:26:40

I posted some pictures of the progress that I have made with a gang tooling fixture for the Tormach PCNC 1100 Mill on the thread "What Did You Do Today" yesterday These showed the fixture plate without tool holders, today I managed to finish the first one.

Here is a picture of the finished fixture without tool hangers.


Here is picture with the first tool hanger fitted and a boring bar mounted on the bottom of it


The tool hangers can be turned through 90 degrees to enable turning tools to be mounted.

Here is a picture of the same hanger turned through 90 degrees and with a parting tool holder attached.


The tool holders are the small size QCTP type, not sure what number they are but they are clheld in position by tightening up four allen cap head screws that draw a dovetail insert into the dovetails of the holder, the insert is visible just below the counterbored bolt hole in the hanger.

I have two more hangers to make and when they are near finished I will mount the fixture in the mill and use the Rapid Turn Lathe attachment to bore out the hangers to accept the Tormach TTS system tooling. I will post some more pictures and vide once done.

Thread: What Did You Do Today (2017)
06/09/2017 17:09:25

Hi Joe,

welder is Mig Gas/No Gas. I also forgot to add that the main box section of the attachment also has mortice & tendon type joints the edges of the mortices were given a 45 degree Chamfer to assist the welding process so basically I have no doubt as to the rigidity & strength of the structure.



06/09/2017 11:29:24

Hi Joe,

It is a hefty construction in 20mm plate. The front plate is 6" deep X 7" long and the side plate is ^" deep x 9" long.

The welds are much better than they look on the picture, preparation included grinding at least a 1/4" 45 degree off the edges that were to be welded this was filled with weld which took well using maximum current, what you see is my attempt to build up in the area of the weld. The biggest problem I have with welding is getting the correct setting for my welding helmet, I am either almost blinded by light or it is too dark to see anything.



05/09/2017 23:17:16

The Tormach CNC Lathe attachment (Rapid Turn) is a much better accessory that it's predecessor which was a Mini Lathe adapted and equipped with 4th Axis capability, however it lacked power to do any serious work.The Rapid Turn is equipped with a 1 H.P. motor and is much more capable, however it lacks multiple tooling capability being equipped only with a single small quick change tool post that clamps to the spindle nose thus rendering it necessary to change tools between different operations.

Other people have made Gang tooling to suit so I decided to have a go at making my own. Here are the results so far.


The holes that you see on the top plate are to permit long allen screws to be fitted into the bearing retain ring, though six holes are drilled only four are used leaving two permanently in the housing the lower plate is attached to two holes drilled and tapped in the rear of the travelling head. Note my scrambled egg welding.

dsc_4283.jpgThis view shows the side of the gang tooling fixture, the holes are all drilled and tapped M 12 to take allen bolts fitted through the tool holders and allow for the holders to be fitted at various heights nd distances along the Y axis.


This view shows the front plate of the fixture, the large tapped hole is there to take the securing bolt from my Quick change Tool post on my BH 600 lathe that I have at least 10 holders.

dsc_4281.jpgThis view shows the two rear holes in the lower plate. A spacer is fitted on top of the machined portion of this plate before the screws are passed through from beneath and screwed into the travelling head.

It's been an interesting project so far. I have started making some tool holders which will be able to take the small size Quick change tools that I bought for the original attachment, these will be height adjustable so I should be able to set them at the same height. They will also be bored to take round shanked tooling such as boring bars and the Tormach modular tooling that have a 3/4" shank dia.

Once I get some of the toolholders finished I will set up the lathe on the mill and take some shots of it and maybe some video of it in action.

Thread: Chinese Electric Cars
14/08/2017 11:27:23

Electric Cars and road vehicles are the future but as many here have said, where is all the power going to come from to charge them all. The government has given the go ahead for new nuclear power generating plant to provide energy for part of our future energy needs at massive cost to the nation.

I Can't help think that the government would be better off providing all households in the UK with solar panels free of charge and investing money into accumulator research so that electricity can be stored in large amounts.

Thread: Key types - any advantages?
10/08/2017 17:43:28

Woodruff cutters are easily made by grinding down an end mill to the correct thickness. I used to use cutters that had maybe chipped a tooth but who,s flanks were still in good condition. They work well.

Thread: What Did You Do Today (2017)
04/08/2017 16:59:09


been there done that got the tee -shirt. I remember sitting in my then, loft model building workshop glueing two wing halves together and trying to get them at the right angle . I kept pouring Cyano onto the joint and heaping Glass balls as a filler to strengthen the joint. It was only when felt the heat very close to the nether regions that I realised that I had a 1/4 scale Flabby monoplane wing joined at the correct dihedral and with a pair of trousers and a human being attached to them.

29/07/2017 15:48:02

As promised the other day. Here is a video of me utilising the Tormach CNC Mill as a slotting machine to cut internal splines in some clutch plates.

26/07/2017 10:22:34

Not Today but yesterday.

I successfully managed to cut some internal splines on a set of clutch plates for a 1920's Alpha Romeo with the Tormach CNC mill using a single point cutting tool. The owner had a set water jet cut but they didn't go anywhere near fitting the splined hub. The hub has 34 teeth, I would imagine that the original plates would have been cut with A broach using a profiled cutter.

The original plates were warped due to overheating and also had radial cracks emanating from a series of 6 radial slots arranged from about half way from the centre to the perimeter of each plate. The plates are 4mm thick at the hub but are reduced from both sides to approximately 1.6mm thick so it is hardly surprising that they warp easily.

The new plates have similar slots but they start from a hole drilled at the root of the slot to prevent cracking in future.

I will post a You tube video once I get time to put together the videos I took while doing the job.

Thread: uPVC door in closed position with broken lock
25/07/2017 07:24:00

Just Make a 999 cal to the policel and tell them you suspect someone has been murdered at your address. Hide in the bathroom before they come.

Thread: Os Gemini twin glow engine - conrod req'd - no longer made
21/07/2017 21:58:53


I know that the big end is a nice fit on the polished shank of a 12mm Carbide cutter. Not sure about the rest though.

21/07/2017 17:55:04


it would be easiest if you were to copy the one I have sent to Mick if he wants to go down that route.

21/07/2017 14:26:32

Hi Mick,

the newer rods are dimensionally identical to the original and are made from tougher bronze than the original type so there is no problem with conversion. I have sent you the old one I had and it will be with you tomorrow. I would recommend fitting the newer type, however, if you can't get them then at least you will have a matching pair of older type rods which will be OK.

If I had to replace the rods I would make a new pair from Aluminium Bronze which is much tougher stuff than the old rods bronze that was originally used. A High Tensile Aluminium Alloy would be best but am not sure how it would affect balance/vibration

20/07/2017 23:05:28

Hi Mick,

I've just finished a session in the workshop but took time out to find the con rod. It was a little battered here and there with a bruise on one of the faces of the little end so I ran an adjustable reamer through it to clean that up.

Three are a couple of marks on it but it looks to be OK. I would gently smooth out these marks to prevent them becoming stress raisers.

Contact me via the message board and let me have your address and I will try to get it in the post on Friday, hopefully you will get it by Saturday, unless of course you live in the South Manchester area and you could always drop by and pick it up.

Here is a picture of it before I ran the reamer through the little end.

On the other side of the big end there are two reference marks 180 degrees apart on the face of it in line with the centre line of the con rod.


18/07/2017 17:45:24


I believe I have an old style con rod from a Gemini Twin, they must be a weak point because my engine snapped one and I replaced it with two of the newer style ones. I am away from home until tomorrow but I will check and if it is still where I think it is I will let you have it F.O.C.


Thread: Timken bearing
09/07/2017 21:28:37

If they are Imperial/old bearings try the Vintage Bearing Company. He deals mainly with cars & Motor Cycles but might well be able to help.

Thread: What Did You Do Today (2017)
23/06/2017 19:19:55

Last week in the hot humid weather we had I had occasion to case harden a couple of gudgeon pins for a veteran Triumph motorcycle. I have never had problems with corrosion in my workshop up till this point.

Once the pins had been soaked for a few hours at 900 degrees Celsius I opened the furnace door to remove them from the pot containing the case hardening compound, then I returned them to the furnace to bring them back up to temperature before qrenching them. This was done with the door open at one end of the workshop.

The next day when I went into the workshop I was greeted with all steel and iron surfaces coated in a layer of rust, All of the TTS nooling for the Tormach Mill had rust on the mandrels that are gripped in the spindle were affected. I spent the whole morning carefully removing the rust with very fine wet or dry paper and giving them all a smear of oil.

I found that the closer to the section of the workshop that houses the furnace the worse the rust coating. I can only assume that this has happened as a result of the very high humidity, lack of air circulation (there was not wind whatsoever on the day) and the fumes from the case hardening compound.

Once bitten, Twice Shy I resolved to not having this happen again so yesterday I ordered a 14" industrial extractor fan. It arrived this morning and I chain drilled a hole in the brickwork for it, knocked out the bricks so that I could fit the fan, fitted it and wired it up.

The neighbours aren't going to like it one bit, it's really noisy but boy does it shift some air. You can feel the draught coming through the curtain doors, hopefully from now on when I use the furnace I won't have a future recurrence of the corrosion.

The fumes from the case hardening compound must be very acidic because even some brass pipe fittings on my model aircraft engine turned a copper colour, as though the zinc near the surface had been eaten away leaving them looking more like copper than brass.

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