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Boring bar

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Paul Cheffings21/10/2019 14:29:24
3 forum posts
1 photos


For years my father has been building engines and repairing clocks as a hobby. Unfortunately he now has Alzheimers and I have been trying to help him finish an engine he started a few years ago.

I have managed to break the insert in a boring bar and wondered if anyone might know where I can obtain a new insert from.

The boring bar has the following number on it UJ 8-803-F-R, the insert is triangular, held in with a very small Torx screw. Measuring the size of the recess I think it would be around 5.5mm across.

I haven't been able to find any information by searching for the reference number on the internet.

Below is a photo of the boring bar. The key is there to stop it rolling so that the number is visible.boringbar.jpeg

Any help would be appreciated.



old mart21/10/2019 16:56:31
2006 forum posts
155 photos

I hope you have saved the bits of the broken insert. These charts may be of help in identifying the exact type.


Paul Cheffings21/10/2019 17:11:55
3 forum posts
1 photos


Unfortunately not as it disappeared and the piece left in the holder was so small you wouldn't be able to get any information from it.



David Standing 121/10/2019 17:19:13
1289 forum posts
48 photos

That appears to be a Komet boring bar.

Take a look at the UJ R (RH) bars and inserts at the bottom of page 306 on the attachment:


old mart21/10/2019 19:10:34
2006 forum posts
155 photos

It is very likely, that the cost of replacement inserts for this bar would far exceed the price of a cheap Chinese bar and inserts.


mechman4821/10/2019 19:19:17
2757 forum posts
424 photos

I have a couple of those boring bars & inserts from the co. in the link as shown in 'Old mart's post, worth the money, & work well.


Ian P21/10/2019 19:30:34
2420 forum posts
101 photos

I have the identical Komet bar (8mm OD) which I bought with ten inserts in 1980something. The original Komet inserts have long since gone and whilst I have fitted other makes none have ever performed as well as the originals and the bar now just sits in a drawer.

I cannot remember the part number for the tiny triangular tips I found, Jenny at JB tooling gave me one as a sample to try so it might be worth contacting her.

Ian P

Paul Cheffings21/10/2019 21:56:22
3 forum posts
1 photos


Thanks to all who have replied. It looks like one of the cheap Chinese boring bars maybe the way to go as although I now know which insert I need I cannot find anywhere that actually sells them.



Howard Lewis21/10/2019 22:03:34
3627 forum posts
2 photos

If you cannot obtain inserts for your bar, at a reasonable price:

Check the dimensions of your bar, and then contact Jenny Blackwell at JB Cutting Tools. She will be able to fix you up with something suitable, no doubt.


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